Learn Spanish (Latin America): Ellos van al centro.

In Spanish, when the preposition a (to) is followed by el (the masculine word for "the"), they must merge to form the contraction al. Because centro is a masculine word (el centro), we use al centro (to the center) instead of a el centro.

Doesn't van mean "they go"? Why is the translation "they are going"?

In Spanish, the simple present tense covers both! Ellos van can mean "They go" as a regular routine, or "They are going" right now. You can usually tell which one is meant from the context of the conversation.

Why is "downtown" translated as centro?

The literal meaning of centro is "center". When people talk about going to el centro, they mean the city center or main commercial district, which we commonly call "downtown" in English.

Is it okay to drop Ellos and just say Van al centro?

Yes! In Spanish, you can often drop the subject if it is understood. However, because van can mean "they go" or "you all go" (ustedes van), keeping Ellos makes it completely clear that you are talking about a group of other people.