Why can't it be the man eats a banana? (I mean grammatically speaking, not just because we're practicing orange)
Yes. "Πορτοκάλι" comes from the italian "portogallo". Portugal was the main source of imports for oranges in the 10th century (after the fruit arrived in Europe from China or India), so the fruit was named after it. :D
Portugal (the country) = Πορτογαλία
Orange (the fruit) = Πορτοκάλι :)
How come the sentence is given away, instead of word for word and sentence grammar?
No. Because it would be "μία μπανάνα" instead of "ένα μπανάνα". Βecause banana is feminine word.
That's because you have a typo in your answer. Men is plural, while you need the singular form of the noun ^.^
It is singular "the man" not plural "the men"! (Ο) Άντρας is singular, (οι) άνδρες is plural.
In English, the verb form changes depending on the number of people doing it: Singular: "The mAn eatS an orange" Plural: "The mEn eat an orange".
I hope this makes sense and helps you!