"What books do you read?"
Translation:Jakie książki czytasz?
Why does it not start with "które"? I thought 'Jakie' was more similar to meaning "how" in English.
You probably meant jak (=how). Usually, które = which. You could use it here if you meant "which of these/those". If you want to ask in general you use jaki (= what in this meaning; what kind of books in general).
Exactly. You would use "które" if you had a finite set of choices, for example if the only books that existed were: a) Harry Potter series, b) LOTR series, c) Twilight series.
Well... I'd say, that "what" kinda functions as an adjective here - as it means "what kind". So "co" is out of the question here, it wouldn't make any sense.
There is a lot of just memorizing and very many light bulb moments when I finally think I get it.
"jakie książki" are in biernik indeed. But as it's 'not masculine-personal' plural, it's identical to Nominative.
I can agree with "genre" (added), but we'd still prefer to keep "what" and not "which" as a direct translation of "jakie".