We count bathrooms by the number of separate rooms, not by the number of fittings. If the toilet is in one room and the bath or shower in another, that is two bathrooms. If everything is in one room, it is one, no matter how large it is.
A guest toilet with only a WC and a small basin still counts as a separate room: it has a floor, tiles, a mirror and sanitary ware, all of which take time.
Each bathroom includes the bath or shower cabin, the WC, the basin, taps, mirrors, tiles, open shelves, the towel rail and the floor. Limescale on the glass and the taps is treated with a dedicated product that needs time to work.
Why this matters for the price: bathrooms are the most labour-intensive rooms in a flat after the kitchen, so the calculator asks for their number separately. If you are unsure how to count yours, describe the layout to the manager before booking.