The Hungarian sentence, "Hogy vannak a nagy almák?" would be asking how the apples feel, but the question was to translate "Milyenek a nagy almák?" In English, "How are the big apples" would mean the same thing as "What are the big apples like," and either would be a correct translation of the Hungarian phrase, in my opinion.
Agreed, this was my suggestion in the singular version of this same question in an earlier lesson. "How are the big apples" should also work here, are you are asking how they taste, etc.
I was wondering about this, as the dictionary say it means "what kind of"