Learn Hardcore Turkish: Ben televizyonu açıyorum.

In Turkish the verb ending already tells you the subject, so Ben (I) is often dropped. You can say simply Televizyonu açıyorum and it still means “I am turning on the television.” Including Ben adds emphasis (“I, personally, am turning it on”) or contrast (“I’m turning it on, not you”).

What does the -u at the end of televizyonu do?

That’s the accusative case suffix marking a definite/direct object. Since you have a specific television in mind (not “television in general”), you attach -u (from the accusative series –ı/–i/–u/–ü). So televizyon becomes televizyonu.

Why isn’t it televizyon without any ending?

If you omit the accusative -u, you still understand “turn on a television,” but it sounds indefinite/habitual (“I turn on televisions”). To refer to a known TV you must use -u. Without it you’d be using the unmarked object form for general statements.

How is açıyorum formed? Which parts are these?

Breakdown of açıyorum:

Root: aç- (to open/turn on)
Progressive aspect: -(I)yor (present continuous)
Person ending: -um (1st person singular “I”)
Combine with vowel harmony: aç
- ıyor
  - um → açıyorum.

Why is it ıyor and not iyor or uyor in açıyorum?

Vowel harmony dictates which vowel appears:

The root vowel in aç- is a (a back vowel), so the progressive suffix uses its back variant -ıyor (not -iyor or -uyor).

Could I say açıyorum for both “I’m turning on” and “I turn on” in a habitual sense?

No. açıyorum specifically conveys an ongoing action right now (“I am turning on”). A habitual/general meaning (“I turn on”) uses the simple present/ Aorist -r: açarım (“I turn on [regularly]”).

How do I pronounce the Turkish ı in açıyorum?

The Turkish ı is a close back unrounded vowel [ɯ], somewhat like the second syllable of English “roses” but tenser. In açıyor-um, the ı in ıyor is pronounced without lip rounding.