Oi, Clayton!! Como vai? :) Yes, nós/nos have different uses and different pronunciation. They are both pronouns. Nós is the subject pronoun and nos is the object pronoun. Examples: Nós viajamos a semana passada (we travelled last week) / Ele nos visitou (he visited us). Hope I've helped :)

Nós is the pronoun we,in English. Nos is an oblique pronoun,that can be used as an object,referring to nós,like: Ajude-nos a aprender inglês.(Help us to learn English). But there are also exceptions,like: The lesson was made by us. (A lição foi feita por nós). Note that,in this case,you don't use nos,because there isn't a verb together with the pronoun.