The other reply has covered what Apple TV is, but for context; some 15 years ago there were regular reports that Apple were about to release their own TV set.
At a glance, this isn’t too dumb; they already had a standalone monitor, and the difference between an iMac and an LCD TV isn’t huge. But give it more than a moment’s thought and you realise that it’s complete bollocks. People replace computers semi regularly because more powerful ones come along. How often do you replace your TV?