Some people have mentioned it already, but I didn't see any answer!
Wouldn't it be more natural to say "She has several cats"? (assuming she has more than two)
And is that also the case in Norwegian, or is the sentence above natural?
Edit: apparently, if I waited a bit I would have learned the word "several". So I'm guessing the sentence is not natural, and is only here to teach us?
The sentence is perfectly natural in either language.
When saying "She has cats" it's obvious that she has at least two and perhaps several cats, but the emphasis of the sentence is not on the number of cats, but rather on her being a cat owner, or there being cats present at her place (think allergies).
When saying "She has several cats", then the number of cats gains importance.