Donald Trump talked about designating Brazil as a major non-NATO ally or even possibly a NATO member, because the US wants to use it as a beachhead for a military intervention in Venezuela. Colombia is already a NATO partner and now the US want to grant the same status to Brazil, to have it ready to implement actions against governments considered undesirable in Latin America, namely Venezuela.
This case is part of a recurring pro-Kremlin narrative about alleged plots against Venezuela.
Designation by the US as a non-NATO ally offers some benefits in the field of military cooperation but it doesn’t imply any obligation to provide bases or troops for operations.
Regarding Brazil becoming a full member of NATO, no evidence was given for such plans. Moreover, Brazil's NATO membership would be unlikely, since it would require all NATO member states agreeing to change Article 10 of the alliance’s 1949 founding treaty, which states that only European countries can join, besides Canada and the United States.
Additionally, Brazilian top military officers and Vice president Hamilton Mourao have repeatedly made clear that they have no intention of allowing a US military intervention from their territory, as recently confirmed by President Bolsonaro himself. The Brazilian Armed Forces keep communication channels open with the Venezuelan army, even though the Brazilian government doesn’t recognise Nicolás Maduro as president.