In order to find out the version of the software you need, you need to connect to the VPS/dedicated server via SSH. And enter the appropriate commands.
To find out the version of PHP:

php -v  

nginx version:

nginx -v  


mysql -V  

On CentOS 6, 7:

httpd -v  

On Debian 7, 8 and Ubuntu 16, 18:

apachectl -v  
Updated Sept. 4, 2019