It's possible the twin beds may already be pushed together, but if not, you can push them together yourselves.
Or if that's not what you want, ASK for "a double bed". If you're booking in France, ask for "un lit matrimonial" - literally, "a marriage bed", but it just means a double.
I have always found it to be 2 sinlge beds with a small unit in the middle but you can move it and put the beds together and they will be left that way during your stay. I find it is better to have these beds rather than a double bed during the summer season as it gives you more space to move and not so hot if both in a double bed, Good Luck
"Twin beds" means two beds, and they may be quite small beds.
Some (some!) hotel rooms with "twin beds" do have them so the two beds can be pushed together. However, you need to call the hotel and talk to a human to ask.
Twin beds: Two separate beds about 6.5 ft long x 3 ft wide.
Double bed: One bed about 6.5 ft long x 6 ft wide.
Now whether the two separate bedrooms each have twin beds or whether each bedroom has one of the two twin beds can't be answered here.
It means one big bed which is made by two pushed together in a one bedroom hotel
trying to book a holiday for me and my boyfriend and most of the rooms are described like '1 Bedroom Apartment
Separate bedroom with twin beds plus a sofa bed in the living area' does this mean two seperate beds or two pushed together for a big bed ?