Hola Elizabeth

I imagine you are referring to this sentence in the lesson:

We are using here the most natural translation in English. In Spanish sometimes we use the present tense (e.g. vuelven) to express a "future" action instead of a regular present action -it depends on the context. This is why in English you have a tense reflecting a future action "are returning" but you have the present tense "vuelven" in Spanish.

 I hope this clarified it.

Saludos

Inma