Fent as in "upstairs" ?
Yes, upstairs.
what is the difference between fent and fellett?
fent is an adverb and stands by itself; felett (only one L - thanks vvsey!) is a postposition and stands after a noun.
A bit like the difference between yukarıda and ...-nin üzerinde in Turkish, I believe.
Similarly with lent versus ... alatt (aşağıda versus ...-nin altında).
okey it is more clear when you explain it in turkish thank you :)
We need to give you specific Turkish explanations, it would be much easier most of the time. :)
Btw, it is felett, not *fellett.
Fixed; thanks!
yes, it can be explained better in turkish
Is there "sleeping room" in English too or only "bedroom"?
No, nobody says "sleeping room" ordinarily, although anybody would know what you meant by that. I think "bedroom" is really the only possibility.
I suppose room (as in my room, your room, etc.) could also work but yeah, you should probably have gone with bedroom