Visa is required for citizens of Brazil to visit Vietnam. Brazilian nationals may have 2 options: Visit Vietnam embassy in Brazil (Brasília) or apply for a visa on arrival to Vietnam from Brazil online. Brazilian citizens may apply for both tourist and business visa to Vietnam for the stay of 1 to 6 months from Brazil. Please check this link for visa fee for Brazilian citizens.

All the information for getting a visa from Vietnam embassy in Brazil can be found here: http://www.vietnamembassy-brazil.org/