Learn Turkish: Saat sekiz. - It is eight o'clock.

In Turkish, you don't need a verb like "to be" (am/is/are) for simple statements like this. Saat sekiz literally means "Hour eight," which is all you need to say "It is eight o'clock."

Is this sentence answering Saat kaç? or Saat kaçta?

This answers Saat kaç? (What time is it?). Because it is just stating the current time, it doesn't take any extra endings. If the question was Saat kaçta? (At what time?), the answer would need to be Saat sekizde (At eight o'clock).

Why does saat come before the number?

When stating the time, Turkish puts the word saat (which means hour, clock, or time) first. It is helpful to think of it as saying "The time is eight" rather than the English order of "eight o'clock."