Üçüncü katta yaşıyorum.

Üçüncü means third.

It comes from the number üç (three) plus the ordinal suffix -üncü. Turkish uses different versions of this suffix depending on vowel harmony:

• bir → birinci = first
• iki → ikinci = second
• üç → üçüncü = third
• dört → dördüncü = fourth

So üçüncü kat literally means third floor.

In Turkish, words that describe a noun usually come before the noun, just like in English.

So:

• üçüncü kat = third floor

Then the location ending is added to the noun:

• kat = floor
• katta = on the floor / on the level

So the full phrase is:

• üçüncü katta = on the third floor

The ordinal üçüncü stays unchanged; the case ending goes on the main noun kat.

-ta is the locative ending. It means in, on, at depending on context.

Here:

• kat = floor
• katta = on the floor

In English we say on the third floor, but Turkish uses the locative ending directly on kat.

Because it is made from:

• kat
  • -ta

The word kat already ends in t, and the locative suffix here is -ta, so when they combine, you get katta.

This is completely normal in Turkish spelling.

The locative suffix has several forms:

• -da / -de
• -ta / -te

Which one you use depends partly on the final consonant of the word.

Since kat ends in the voiceless consonant t, the suffix becomes -ta rather than -da.

So:

• evde = at home
• okulda = at school
• parkta = in the park
• katta = on the floor

Because Turkish verbs usually already show the subject.

Yaşıyorum means I live / I am living, and the ending -um tells you the subject is I.

So:

• yaşıyorum = I live
• yaşıyorsun = you live
• yaşıyor = he/she/it lives

You can say Ben üçüncü katta yaşıyorum, but ben is often omitted unless you want emphasis.

Yaşıyorum comes from the verb yaşamak, which means to live.

It breaks down roughly like this:

• yaşa- = live
• -ıyor / -iyor / -uyor / -üyor = present continuous marker
• -um = I

So yaşıyorum literally looks like I am living, but in Turkish this form is also commonly used where English would simply say I live.

That is why Üçüncü katta yaşıyorum is naturally translated as I live on the third floor.

This happens because of how the -iyor/-ıyor/-uyor/-üyor tense ending attaches to some verbs.

With yaşamak, the stem is yaşa-. When this tense ending is added, the final vowel changes so the result is:

• yaşa-
  • -ıyor
    • -um → yaşıyorum

So this is just the normal conjugated form. You do not say yaşayorum.

Yes, very often.

Both can work, but there is a slight difference:

• yaşamak = to live
• oturmak = to sit, but also very commonly to live/reside

So:

• Üçüncü katta yaşıyorum = I live on the third floor
• Üçüncü katta oturuyorum = I live on the third floor / I reside on the third floor

In everyday Turkish, oturmak is extremely common for talking about where someone lives.

Usually yes for some English speakers, but not for all, because floor numbering differs by region.

In Turkey, the ground level is often called:

• zemin kat = ground floor
• giriş kat = entrance floor

Then:

• birinci kat = the floor above ground
• ikinci kat = the next one
• üçüncü kat = the next one after that

So this matches British English style more closely than American English style.

A rough pronunciation guide is:

ue-chuen-jue kat-ta yah-shuh-yo-rum

A few important sounds:

• ü = a front rounded vowel, somewhat like the u in French tu or German über
• ç = ch as in chair
• ş = sh as in shoe
• ı = a vowel that does not exist in English; it is like a relaxed, back i sound

So pay special attention to:

• üçüncü
• yaşıyorum

Those are usually the hardest parts for English speakers.