수건 하나 더 주세요.
sugeon hana deo juseyo.
One more towel, please.
Why this spelling
This romanisation is not the spelling copied letter by letter. It is built from the National Institute of Korean Language’s Revised Romanization, which writes what the word sounds like once the sounds next to each other have changed it.
When you would say it
Ask at the counter on your way in, or at the desk inside if there is one.
Where the clothes come off, and where they go back on
Here is the whole chapter in one line. Past the locker room door, on the wet floor, people are naked, and men and women are in separate rooms with separate entrances. A swimsuit is not an option there, and it is not something the staff can waive for you. That room is built for washing, and the design assumes bare skin.
From the same chapter
The Bathhouse and the Jjimjilbang
Card number 56 of the book
The guidebook prints these as numbered cards, so you can hold up a number instead of trying to pronounce it. The Korean edition comes with it and has the same numbers in the same places.
See the guidebook