This is the 9204th most frequent Portuguese word.
camisetas
T-shirts.
The word 'camisetas' here refers to t-shirts as the subject of the sentence, describing their characteristic of being colorful.
As camisetas na loja são muito coloridas.
The t-shirts in the store are very colorful.
'Camisetas' in this sentence is the object of the verb 'comprei' (bought), indicating what was purchased.
Eu comprei três camisetas ontem.
I bought three t-shirts yesterday.
In this case, 'camisetas' is the object of the verb 'dobrar' (to fold), specifying the items that need folding.