What is the mu-plugins directory in my WordPress site?
Please keep in mind that WordPress is a third party application. Support for WordPress installations is provided through the WordPress community. cPanel is providing the following information as a courtesy.
The mu-plugin directory stores "Must Use Plugins". These are plugins that are always enabled and cannot be disabled through the user interface. In order to disable these plugins, they must be moved out of the mu-plugin directory.
More information can be found here:
WordPress Documentation - Must Use Plugins