Learn Portuguese (Portugal): Nós comemos mais tarde.

In Portuguese, there isn't a single word for "later". Instead, you literally say "more late" (mais tarde). Mais means "more" and tarde means "late" (it is also the word for "afternoon").

If this sentence is the answer, how would I ask "When do we eat?"

You would ask Quando comemos?. To ask "At what time do we eat?", you would say A que horas comemos?. In Portuguese, you do not need a helper word like "do". You simply put the question phrase right before the verb.

Why does the verb end in "-emos"?

Comemos comes from the verb comer (to eat). For regular verbs ending in "-er", the "we" form (nós) always ends in "-emos" in the present tense.

Do I always have to include the word nós?

No, it is completely optional. Because the verb comemos only ever goes with nós, Portuguese speakers often drop the pronoun and just say Comemos mais tarde.