Meus pais s o italianos. My parents are Italian. Temos muitos parentes . We have many relatives . Both prepositions are very often confused as they sometimes have the same meaning in English.
Para also means to , for and in order to.
Por is very often used in idiomatic expressions, along with some verbs, as the agent of the passive voice or even to indicate time. In this case, its use is optional and it is normally omitted. Only with time and some practice can you use them correctly. We are going to Brazil. Vou dar este livro para ela.