Breakdown of Perché tornano in albergo tardi?
l'albergo
the hotel
in
in / made of (material)
perché
because, why
tornare
to return
Questions & Answers about Perché tornano in albergo tardi?
Does perché mean both "why" and "because"?
How do we know the sentence is about "they" if the word loro isn't there?
The verb ending tells us. Tornano is the "they" form of tornare (to return). In Italian, you usually drop the subject pronoun because the verb's ending already makes it completely clear who is doing the action.
Why is it in albergo and not all'albergo?
For certain common places, Italian uses the preposition in without adding a word for "the" (the definite article). You will learn these as set phrases, such as in albergo (to/in the hotel), in banca (to/in the bank), and in centro (to/in the city center).