Run the following command to get the version of PHP installed on Ubuntu machine:
php -version
The output should look like this:
PHP 7.4.3 (cli) (built: Mar 2 2022 15:36:52) ( NTS ) Copyright (c) The PHP Group Zend Engine v3.4.0, Copyright (c) Zend Technologies with Zend OPcache v7.4.3, Copyright (c), by Zend Technologies
Above, 7.4.3 is the version of PHP installed.