Learn Spanish (Latin America): El comedor está aquí; el baño no. - The dining room is here; the bathroom is not.

We use está because we are talking about the location of a specific place: el comedor (the dining room). If we were talking about an unspecific place, like 'There is a dining room here', we would use hay: Hay un comedor aquí.

Why does the second half just say el baño no?

Just like in English, Spanish often leaves out words that are already understood so you do not repeat yourself. The full sentence would be el baño no está aquí (the bathroom is not here), but shortening it to el baño no sounds much more natural.

Does not the word no usually go before the verb?

Normally, yes! In a full sentence, it would be el baño no está aquí. Because we dropped the verb (está) and the location (aquí), we are just left with the subject (el baño) followed by the negative word (no).

Why does aquí have an accent mark?

The accent mark tells you which part of the word to emphasize. It shows that you should stress the last syllable (ah-KEE). Without the accent mark, the standard rules of Spanish pronunciation would make you stress the first syllable.