Since 1994, the Brazilian currency is Real (R$). In Brazil, exchange operation means exchanging a foreign currency for its counter value in Brazilian currency. For example, when a tourist travels abroad and need foreign currency, a Central Bank authorized agent receives Brazilian money and gives back (sell) foreign money. But when a foreign tourist needs to exchange money into Reais, a Central Bank authorized agent buys his money and gives back Reais.
The following institutions are authorized to work in the exchange market: Banks, credit society, financing society and investment society, brokerage companies, distributors, travel agencies and Central Bank authorized lodgings.

In Brazil, presenting ID and CPF (for Brazilians) and passport (for foreigners) is required.

Currency conversion:
Banco Central do Brasil (Central Bank of Brazil)
http://www5.bcb.gov.br/?CONVMOEDA
 
Exchange:
Banco Central do Brasil (Central Bank of Brazil)
http://www.bcb.gov.br/?CAMBIO
BANCO DO BRASIL
www.bb.com.br