Why it isn't "And what are those groups?"
The verb in the sentence is "font", a conjugation of "faire", meaning "to do" or "to make". If the question was asking what the groups "are", the verb used would be "etre" not "faire".
When you hover over it duolingo says are or are in. very confusing.
why can't I begin with and?
Why not -- and what makes these groups?
That would mean something different, you would then assume the groups to be an object, not a subject of the sentence. Generally in English it is pretty important to have the subject before the verb.