<form action="#" method="POST">
<input class="form-control" placeholder="İsim" type="text" name="isim">
<input class="form-control" placeholder="Soyisim" type="text" name="soyisim">
<input type="submit" name="formSubmit" value="gönder">
</form>
<?php
if(isset($_POST['formSubmit'])){
$name = $_POST['isim']." ".$_POST['soyisim'];    
echo $name;
}
?>