There's no such thing as Brazilian (language). They speak Portuguese, or Brazilian Portuguese to be exact.
Word negro is used to describe black people, see
https://pt.wiktionary.org/wiki/negro
Preto is a synonym of negro also used for describing black people (it can bear a pejorative connotation or not. It depends on the context) but generally for things that are black.
The pejorative connotation pertains to a black servant or a black slave:
(racismo) serviçal residencial negro
(racismo) escravo negro
See the note on
https://pt.wiktionary.org/wiki/preto
"In meaning 1, when referring to a human being, it is sometimes considered pejorative, especially when said by a white person. However, there are groups of black people who claim the use of preto. For these people, preto is not only not offensive, but is the most appropriate term. The possibly offensive nature of this word must be analyzed by context."