Thank you Alex. Could I also say у мой комнаты есть пять огромных окон?

It'd be grammatically correct to say В моей комнате есть пять огромных окон.

Thanks! Do you mostly use y with people?

Sorry, my Russian isn't that good yet.

Thanks, man, that's really helpful. Just one thing - a window is external and non-physical. But I guess it just makes more sense to say that parts of a room are "in" the room from a Russian perspective. I've learned that you can't always apply English logic to Russian.