The Brazilian currency is the Real ("hay-ahl"), and Reais ("hay-ice") for the plural. The symbol for the Real is R$. The official exchange rate is published daily in the newspapers. For today's rate see:

http://www.bloomberg.com/analysis/calculators/currency.html

Bank notes in circulation are the following:
R$ 1, R$2, R$5, R$ 10, R$20, R$ 50 and R$ 100

Coins in circulation are the following
R$ 0,01 - R$ 0,05 - R$ 0,10 - R$ 0,25 - R$ 0,50 - R$ 1,00

U.S dollars are easily exchanged at banks, travel agencies and currency exchange offices. Do not exchange money outside Brazil because this is often more expensive. Exchange money in Porto Alegre airport, at least for transportation to SESC. Most bussiness doesn't accept US Dollars or another foreign currency.

Credit cards are widely accepted in Porto Alegre, however, it is advisable to exchange some money before your trip.

Most Brazilian banks offer ATMs, however some foreign cards may not be accepted.