One masculine plural pattern is أَفْعَلُونَ, adding the nominative sound-masculine plural ending -ūna.
Word / formMeaning / explanation
أَكْبَرُونَbigger/greater men.
أَصْغَرُونَsmaller men.
أَعْلَمُونَmen who are more knowledgeable.
The textbook exercise asks for the meaning of أَعْلَمُونَ. Although its lexical quality relates to knowledge, the form is a masculine plural comparative noun/adjective, not a past-tense verb.