Merhabalar. Yaklaşık 6 saattir çözmeye çalıştığım başlıktaki hatayı sizlere de danışmak istedim. Şimdiden çok teşekkürler.
Datanın alındığı yer

$('#registerForm').on('submit', function (e){
    e.preventDefault();
    var registerData = $(this).serialize();
    $.ajax({
        method: 'POST',
        url: '/register',
        data: registerData
    }).done(function (response){
        console.log(response);
    });
});

Datanın alıp iletildiği yer

public function Register(){
        unset($_POST['WHERE']);
        $data = $_POST;
        $this->save('users', $data);
    }

İşlemin yapıldığı yer

namespace app\root;

class Database
{
    protected \PDO $db;
    public function __construct()
    {
        $this->db = new \PDO('mysql:host=localhost;dbname=farmroad;charset=utf8', 'root', 'xxx');
        $this->db->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);
    }
    public function save($table, $data)
    {
        $columns = $this->findColumns($data);
        $params = $this->findParams($data);
        $statement = $this->db->prepare("INSERT INTO $table($columns)VALUES($params)");

//        echo '<pre>';
//            var_dump($statement, $columns, $params);
//        echo '</pre>';
//        exit;
//        $bindPrepared = explode(',', $columns);
        foreach ($data as $final => $value) {
            $statement->bindValue(":$final", $value);
            var_dump($statement, $final, $value);
        }
        $statement->execute();
    }
    public function findColumns($data)
    {
        $enc = '';
        foreach ($data as $final => $values) {
            $final = $final.',';
            $enc .= $final;
        }
        return rtrim($enc, ',');
    }
    public function findParams($data)
    {
        $keys = array_keys($data);
        $sync = '';
        foreach ($keys as $key => $value){
            $sync .= ':'.$value.',';
        }
        return rtrim($sync, ',');
    }
}

var_dump çıktısı

object(PDOStatement)#8 (1) {
  ["queryString"]=>
  string(274) "INSERT INTO users(name,surname,mail,phone,password,confirm-password,province,district,neighborhood,born_day,born_month,born_year,gender)VALUES(:name,:surname,:mail,:phone,:password,:confirm-password,:province,:district,:neighborhood,:born_day,:born_month,:born_year,:gender)"
}
string(4) "name"
string(6) "İslam"
object(PDOStatement)#8 (1) {
  ["queryString"]=>
  string(274) "INSERT INTO users(name,surname,mail,phone,password,confirm-password,province,district,neighborhood,born_day,born_month,born_year,gender)VALUES(:name,:surname,:mail,:phone,:password,:confirm-password,:province,:district,:neighborhood,:born_day,:born_month,:born_year,:gender)"
}
string(7) "surname"
string(4) "Saka"
object(PDOStatement)#8 (1) {
  ["queryString"]=>
  string(274) "INSERT INTO users(name,surname,mail,phone,password,confirm-password,province,district,neighborhood,born_day,born_month,born_year,gender)VALUES(:name,:surname,:mail,:phone,:password,:confirm-password,:province,:district,:neighborhood,:born_day,:born_month,:born_year,:gender)"
}
string(4) "mail"
string(20) "islamsaka@icloud.com"
object(PDOStatement)#8 (1) {
  ["queryString"]=>
  string(274) "INSERT INTO users(name,surname,mail,phone,password,confirm-password,province,district,neighborhood,born_day,born_month,born_year,gender)VALUES(:name,:surname,:mail,:phone,:password,:confirm-password,:province,:district,:neighborhood,:born_day,:born_month,:born_year,:gender)"
}
string(5) "phone"
string(12) "533 127 0000"
object(PDOStatement)#8 (1) {
  ["queryString"]=>
  string(274) "INSERT INTO users(name,surname,mail,phone,password,confirm-password,province,district,neighborhood,born_day,born_month,born_year,gender)VALUES(:name,:surname,:mail,:phone,:password,:confirm-password,:province,:district,:neighborhood,:born_day,:born_month,:born_year,:gender)"
}
string(8) "password"
string(8) "jsX.2345"
object(PDOStatement)#8 (1) {
  ["queryString"]=>
  string(274) "INSERT INTO users(name,surname,mail,phone,password,confirm-password,province,district,neighborhood,born_day,born_month,born_year,gender)VALUES(:name,:surname,:mail,:phone,:password,:confirm-password,:province,:district,:neighborhood,:born_day,:born_month,:born_year,:gender)"
}
string(16) "confirm-password"
string(8) "jsX.2345"
object(PDOStatement)#8 (1) {
  ["queryString"]=>
  string(274) "INSERT INTO users(name,surname,mail,phone,password,confirm-password,province,district,neighborhood,born_day,born_month,born_year,gender)VALUES(:name,:surname,:mail,:phone,:password,:confirm-password,:province,:district,:neighborhood,:born_day,:born_month,:born_year,:gender)"
}
string(8) "province"
string(1) "1"
object(PDOStatement)#8 (1) {
  ["queryString"]=>
  string(274) "INSERT INTO users(name,surname,mail,phone,password,confirm-password,province,district,neighborhood,born_day,born_month,born_year,gender)VALUES(:name,:surname,:mail,:phone,:password,:confirm-password,:province,:district,:neighborhood,:born_day,:born_month,:born_year,:gender)"
}
string(8) "district"
string(1) "1"
object(PDOStatement)#8 (1) {
  ["queryString"]=>
  string(274) "INSERT INTO users(name,surname,mail,phone,password,confirm-password,province,district,neighborhood,born_day,born_month,born_year,gender)VALUES(:name,:surname,:mail,:phone,:password,:confirm-password,:province,:district,:neighborhood,:born_day,:born_month,:born_year,:gender)"
}
string(12) "neighborhood"
string(1) "1"
object(PDOStatement)#8 (1) {
  ["queryString"]=>
  string(274) "INSERT INTO users(name,surname,mail,phone,password,confirm-password,province,district,neighborhood,born_day,born_month,born_year,gender)VALUES(:name,:surname,:mail,:phone,:password,:confirm-password,:province,:district,:neighborhood,:born_day,:born_month,:born_year,:gender)"
}
string(8) "born_day"
string(1) "1"
object(PDOStatement)#8 (1) {
  ["queryString"]=>
  string(274) "INSERT INTO users(name,surname,mail,phone,password,confirm-password,province,district,neighborhood,born_day,born_month,born_year,gender)VALUES(:name,:surname,:mail,:phone,:password,:confirm-password,:province,:district,:neighborhood,:born_day,:born_month,:born_year,:gender)"
}
string(10) "born_month"
string(1) "1"
object(PDOStatement)#8 (1) {
  ["queryString"]=>
  string(274) "INSERT INTO users(name,surname,mail,phone,password,confirm-password,province,district,neighborhood,born_day,born_month,born_year,gender)VALUES(:name,:surname,:mail,:phone,:password,:confirm-password,:province,:district,:neighborhood,:born_day,:born_month,:born_year,:gender)"
}
string(9) "born_year"
string(4) "2000"
object(PDOStatement)#8 (1) {
  ["queryString"]=>
  string(274) "INSERT INTO users(name,surname,mail,phone,password,confirm-password,province,district,neighborhood,born_day,born_month,born_year,gender)VALUES(:name,:surname,:mail,:phone,:password,:confirm-password,:province,:district,:neighborhood,:born_day,:born_month,:born_year,:gender)"
}
string(6) "gender"
string(1) "2"