A "set of bunk beds" refers to two beds that are stacked on top of each other. It is like a bed with two levels, where one bed is on top and the other is underneath it. Full definition
Has one double and 1 set of bunk beds Rooms # 10 and 11. (crystalparadise.com)
The third bedroom is ideal for children, with a modern set of bunk beds featuring alongside a modern desk and contemporary en - suite shower room. (fenicehospitality.com)
Bedroom 6: Two charming sets of bunk beds sleep four children (that is, if they ever go to sleep). (house-parties.com)