Why is it that Apple TV has charges even though I have a 12 month subscription

if you mean why some things cost money then it's because your subscription is for appletv+ which is apple produced material

not all the third party material apple host for other content providers, those you still have to purchase or rent

you can read about apple tv+ here https://www.apple.com/apple-tv-plus/

An Apple TV+ subscription covers just the Apple Original content.

It does not include content from the iTunes Store (movies for buy or rent).