"في ٱلْطّابِق اَلْأَوَّل حَمّام."
Translation:There is a bathroom on the first floor.
Actually it depends on which country you are in. Also it can mean both in tge same country.
In Arabic, when the subject of a nominal sentence (one whose English translation uses verb "to be") is indefinite, the predicate is moved to the beginning of the sentence. So "حمام في الطابق الأول" wouldn't make any sense. Compare how in English, you would say "On the first floor is a bathroom." but not "A bathroom is on the first floor."
Thank you for the reply and excellent grammar note.
Clarification on the English examples on last two lines: English has no problem(grammar, syntax, or usage) in saying, "A bathroom is on the first floor". It is a declarative sentence.
Example: A young child finds the doorman outside and states, "Excuse me sir, I need a bathroom." "A restroom is on the first floor", replies the doorman with a gentle smile. In American English you can produce subtext with word selection, colocation and syntax/word order. I had thought this was possible in the Arabic language also, however, not necessarily direct correlation exists in both languages. Such as, the same word order in both languages may not produce a subtext or inference with a common meaning (if any meaning other than the speaker is not native) or effect upon the receiving party/audience. It could be useful to know that this exists in the Arabic Language, if it exists: Communications to inform, Communications to relate, Communications to influence...
Hammam can mean both; WC and bathroom. In formal conversations we use hammam for WC.