How Apple TV works?

the appletv is sort of like an ipad that use your tv as it's screen, anything it does is because of apps in app store that content providers add to apples app store

Too Embarrassed to Ask: What Is Apple TV, Anyway? - Vox

Apple has many offerings for TV. You can find them at www.apple.com/TV. Some are hardware and some software. The bad news... it can be confusing as they all have similar names. Below is a brief overview of Apple TV offerings:

Apple TV+ is $4.99 per month service, everything else in the Apple TV app are additional charges. If you are unclear on what the difference is between Apple TV+ and what the Apple TV app is it's pretty simple.

• The Apple TV app is simply a single place to buy content, including Apple TV+ content, Showtime, Paramount + and lots of other content. 
• Apple TV + is Apple's own proprietary content, currently it is a small library of content which is why it is in-expensive. The good news is the library is constantly growing and adding some really good content!

Still confused? Please visit www.apple.com/tv and look over Apple's TV offerings which include:

•  Apple TV HD (hardware)
• Apple TV 4K (hardware)
• Apple TV app (as described above)
• Apple TV + (as described above)
• AirPlay
• Accessories

Please feel free to ask more questions.