Most apartments have one or more bedrooms with real beds and a living room with two extra beds (usually a sofabed). Studio apartments are usually equipped with only a sofabed. Do not count on extra beds having the same comfort as the regular beds. In some cases, the additional bed can be a part of the ordinary bed.
In Southern Europe and the US it is common for a bed to be about 140-180 cm wide, designed for two people, a so-called Grandlit. It is also common that the beds are about 180 cm long. There may be bunk beds. In some accommodations it is possible to bring a child under 3 years of age (in some cases two years ) in addition to the maximum number specified. If it is possible to rent a cot for children under 2 years, it is stated in the description.