"I have several uncles."
Translation:Jag har flera morbröder.
Out of curiosity, is there a way to say "I have several uncles" that refers to both maternal and paternal uncles, or do I actually have to say "Jag har flera morbröder och farbröder" in this case?
You'd have to use the inclusive morbröder och farbröder (or in reverse order). There is the cognate onkel, but it is borderline archaic and I wouldn't expect to ever come across it outside of older literature.
The plural is morbröder. It's the same with bror: en bror, flera bröder 'one brother, several brothers'.
Because ”several” rather translates to ”flera” than ”många”. But the ”farbröder” part is correct.