We can't really call it anything else and feel honest -- it is a small bedroom.  It has a generous full-sized (not double) bed.  It doesn't have a closet but has plenty of shelving for storage.

In this picture, the wall bordering the large bathroom is on the left, and the hallway is at the end of the room on the left.  There is a window onto the courtyard behind, so this room has the advantage of being cool and quiet.