What is the charge of $4.99 for Apple TV relate to?

And just to remind you, you have to sign up for that subscription, it doesn’t not automatically start for no reason. You may have been offered a free trial that became a paid subscription if you did not cancel it after the trial period.

That entitles you to watch all Apple TV+ content for no additional charge. See https://tv.apple.com/

It does not include Apple TV content that is not part of Apple TV+