"The cats drink milk."
Translation:Katterna dricker mjölk.
The translation for "the cats" says "Katternas" but should it not be "Katterna" ?
Yes ”katterna” is the cats whereas ”katternas” is the cats’ (possessive).
This looks right in the incubator. It might be due to a known bug though, there's a problem with adding hints to words with apostrophes. So maybe the hint for the word the cats' is being shown to you here. Duo knows about this problem but there's nothing more we can do about it.