"Nosotros comemos muchas manzanas en el verano."
Translation:We eat a lot of apples in the summer.
Because you cannot use the present continuous tense (present form of the verb “be” + the present participle of a verb) to describe events that happen normally, or for a long time. E.g., you can say "I am playing rugby on Saturday afternoon" as it is happening once on one Saturday afternoon only. However, you cannot say "I am playing rugby on Saturday afternoons," as it's an ongoing event that happens normally on ongoing Saturdays. Instead, you have to say "I play rugby on Saturday afternoons." (native British English speaker)
Yeah, that would be better because apple is generally late summer or autumn fruit. But then again Duo has sentences about bears washing and whatnot.