"Her sweatshirt is colorful."
Translation:Jej bluza jest kolorowa.
isn't 'bluza' blouse in English? Besides, the question stated that 'sweter' was correct for some reason.
The word blouse is in Polish bluzka and sweter is made from wool , when bluza is made from cotton or something like that
Her - when to use je and when to use jej why isn't je bluza jest kolorowa correct?
"je" does not mean "her".
With "his", "her" and "their" everything is super easy - all forms are the same.
"je" is Accusative of "they" (so "them") for not masculine-personal plural. For example "Widzę je" (I see them), when there isn't any man among 'them'.