"Est-ce que" in front of any declarative sentence make it a question. There are several ways to make questions in French, this is just one and probably the most "polite" way. Literally, it means something like "Is it that" - so here, the sentence could be translated "Is it that you are at the hotel?"
"Est-ce que" in front of a declarative sentence turns it into a question. It literally means "Is it that", so here the sentence could be translated as "Is it that you are at the hotel?" There are several ways of asking questions in French, but using "Est-ce que" plus a declarative sentence is the most polite form, as well as easy to do!