Traffic signs in Brazil, as well as most South American countries, is heavily based on US traffic signs, but with Portuguese texts. Regulatory signs, prohibition and mandatory are all white circular with red borders, except for the stopping and the sign "Give preference." Warning signs are shaped yellow diamond (or orange when indicate signaling works).
This application will help you solve the traffic signs on the roads. friendly interface helps you quickly locate a particular sign in the right section.
Attached is the most current information on road signs.