Translation:My cousin has a nice blue skirt.
You are maybe confusing Krásný(beautiful) with Hezky(nice)? I know I do that.
I wouldn't use cute for those though. Maybe with hezky but I'm not sure.
My strategy with duo is to try and learn the closest thing to a 1:1 translation and use that for the course(even if it means unnatural english) and then when you start speaking with natives it's pretty easy to learn the expanded scope of a word's meaning.
If you're having nuance issues with translations here. Steel yourself because it doesn't get better, especially in this course specifically.
You could call a skirt (and some other inanimate things) "cute" in English, at least in the US, and I will be happy to add it here -- unless, from the Czech side, there is a reason not to. One thing to remember, in general, is that hezký should not be used to mean "nice" when referring to people. There's lots of discussion about that sprinkled throughout the forums.