Usages of os
Eles ganharam o jogo ontem, e o treinador os parabenizou.
They won the game yesterday, and the coach congratulated them.
Eu os vejo na cidade todos os dias.
I see them in the city every day.
As alunas cujos cadernos ficaram na sala vão buscá-los amanhã.
The female students whose notebooks were left in the classroom are going to get them tomorrow.
Elon.io is an online learning platform
We have an entire course teaching Portuguese grammar and vocabulary.