"Her sweatshirt is colorful."

Translation: Jej bluza jest kolorowa.

[Roberto617143]

Sweter = sweater, not Sweatshirt

[podeksiemieniem]

The word sweter has not the same meaning as the word bluza

[Roberto617143]

isn't 'bluza' blouse in English? Besides, the question stated that 'sweter' was correct for some reason.

[podeksiemieniem]

The word blouse is in Polish bluzka and sweter is made from wool , when bluza is made from cotton or something like that

[margotgm]

Her - when to use je and when to use jej
why isn't je bluza jest kolorowa correct?

[Jellei]

"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'.

[Zack41690]

could it be

ona ma kolorowej bluzy/bluzi (not sure)

[alik1989]

Ona ma kolorową bluzę (accusative case), sure.

But that's a different sentence.

[Jellei]

and out of those two versions, "bluzy" is an existing form. But incorrect in your sentence, as Alik pointed.