As a preposition:
* Of: "O livro de João" (The book of John).
* From: "Vim de Portugal" (I came from Portugal).
* About: "Falar de política" (To talk about politics).
* With: "Ele está de férias" (He is on vacation).
* By: "Casa de madeira" (House made of wood).
* For: "Ele é de Lisboa" (He is from Lisbon).
As a part of a compound word:
* De + adjective/noun = "a" or "some"
* "De manhã" (In the morning)
* "De repente" (Suddenly)
* "De repente" (All of a sudden)
As part of a grammatical construction:
* De + infinitive = "to"
* "Vou de comer" (I am going to eat).
* De + noun = "some" or "a"
* "De água" (Some water)
* "De pão" (Some bread)
It's important to consider the surrounding words and the context to determine the best English translation for "de".