As a preposition:
* of: This is the most common translation for "de" when it acts as a preposition. For example: "un libro de historia" (a history book) translates to "a book of history."
* from: "De Madrid a Barcelona" (from Madrid to Barcelona)
* by: "Un libro escrito de Shakespeare" (a book written by Shakespeare)
* about: "Una película de amor" (a love movie) translates to "a movie about love."
* in: "Un día de lluvia" (a rainy day) translates to "a day in the rain."
As part of a possessive adjective:
* my, your, his, her, its, our, their: "Mi casa" (my house), "tu libro" (your book), etc.
As part of a compound noun:
* Often translated as a single word: "un portafolio de inversión" (an investment portfolio)
* Sometimes translated separately: "un hotel de lujo" (a luxury hotel)
It's important to consider the context to determine the best English translation for "de."
If you provide a sentence with "de" in it, I can give you a more specific translation!