There's a designated building for it, much shorter and more spread out than most other places they've seen, with large tanks on the roof. Inside, there are two separate sections that look fairly similar to each other in composition, although one is maybe twice the size of the other. Each one has a sign out front with what looks like pricing information, and with their rudimentary reading skills they can discern that the larger one is slightly more expensive. There's a pot under the sign; Lornell deposits some coins in it. There doesn't seem to be anyone conspicuously hanging around it to deter theft or ensure people pay.
Past the sign are several corridors, each lined with small rooms. The doors of each have frosted glass windows that ensure privacy but still let in enough light to see by. On entering, it becomes clear that each room is in fact two smaller ones, separated by a curtain. The first has a bench and hooks for hanging clothes, with neatly-hung clean towels on a rack. The second has the actual showering apparatus, a washcloth, three metal liquid soap and hair product dispensers of differing sizes (each stamped with a single word, which Lornell taught them to distinguish on the way over), and a drain in the floor.
There are separate handles for hot and tepid water, which allow a reasonable amount of temperature control. The water pressure is basically non-existent, though; it seems to be powered by just gravity. From the amount of sound coming from the other rooms they might be able to discern that people don't seem to be running the water the whole time they're in there; they might be soaping up with the water off and mainly using it to rinse off.