<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script>
$(document).ready(function(){
  var isim = $('#isim').text();
  var soyisim = $('#soyisim').text();
  var intials = $('#isim').text().charAt(0) + $('#soyisim').text().charAt(0);
  var pp = $('#pp').text(intials);
});
</script>
<style>
#pp {
  font-size: 55px;
  font-family: Poppins;
  font-weight: 600;
  width: 150px;
  height: 150px;
  border-radius: 50%;
  background: #512DA8;
  color: #fff;
  text-align: center;
  line-height: 150px;
}
</style>
<span id="isim" style="display: none;">Furkan</span>
<span id="soyisim" style="display: none;">Tastan</span>
<div id="pp"></div>