I am not sure the difference between "single" rooms and "double rooms" I am assuming they are referring to f guests, not type of beds. Sorry if silly.

single - one person
double - 2 persons
triple - 3 persons

Double does not mean two beds.

It's never a bad idea to ask what beds are provided in a room described as "single", "double for single use", "double", "twin", "triple" or any other description.

Only generalization that seems universally true is that a "single" room is not meant to be occupied by two guests, regardless of what beds it may contain.

Best wishes,

Rex

In Europe a single often means a tiny room with one single bed (like you had when you were a child).

A double is a room for two people - which may have one double bed or two twin beds (the latter may also be called a "twin" room).

A triple is a room that holds 3 people - but you need to ask specifically to find out what the bed arrangement is (one double and one single, 3 singles)?