The optional module, intl, is not installed, or has been disabled.

If you are using ubuntu you can take update

$ sudo apt-get update

And install extension in case of php 5.6

$ sudo apt-get install php5.6-intl

And in case of php 7.0

$ sudo apt-get install php7.0-intl

And in case of php 8.1

$ sudo apt-get install php8.1-intl

And restart your apache after

$ sudo service apache2 restart

And restart your nginx after

$ sudo systemctl restart nginx

If you are using xampp then remove semicolon ( ; ) in xampp/php/php.ini from below line

 ;extension=php_intl.dll