booking a hotel

Tony, As the others have mentioned, you'll need to book a double for both of you. I often travel solo, and the rooms I'm assigned are often somewhat "compact" with a single bed, which is not suitable for two (although occasionally I get a "double for single use"). Cheers!

It's a double. A single is a room for one person. A double is a room for two people.

In Europe, maybe in particular in Germany, hotels often have rooms with a single twin bed for just one person. A double room might have two separate twin beds or a double bed which is actually two twins pushed together. A room with two queen or king beds, suitable for four people, is rare.