Brazilian currency is the Real (or Reais when plural) and is written as R$.

1. Note denominations are: 100, 50, 10, 5 & 1 REAL
2. click on the image to enlarge
   Coin denominations are: 1 Real, 50, 25, 10 & 5 centavos.

US dollars are easy to change in the banks and any exchange house.  And generally, US dollars are accepted as payment in the luxury hotels, up market restaurants, tour companies and some souvenir shops in the larger cities.