"Which room" is how you ask which specific room in English. If you want to ask about a specific room, you can say "Which room is this?" or "Excuse me, which room is this one?"
If you want to ask about multiple rooms, you can say "Which room are we in?" or "I think we're in the wrong room. Which room is it again?"
If you want to ask about all the rooms in a certain area, you can say "Which room numbers are available?" or "What rooms are available for rent in this building?"
I hope that helps! Let me know if you have any other questions.
