What is it and how can I make changes in the php.ini file?

The php.ini file is one of the configuration files that contains the values of PHP directives such as: max_execution_time, memory_limit, max_upload_size, and so on.

Below you can find tutorials for editing this file, for each type of hosting (shared or vps):

Editing the php.ini file on shared hosting spaces with cPanel
Editing the php.ini file on VPS hosting spaces with cPanel
Editing the PHP directive disabled_functions on shared hosting spaces with cPanel

If the PHP directive/setting you want to modify is not found in the editing interfaces of php.ini, you will need to contact the technical department for changing the settings at the server level.