Brazil has a variety of electrical voltages, sometimes within the same city.  Outlets often accept a variety of plug types, as does the one above (seen at a hotel built in the late 1990s in Salvador, Bahia).  For this reason, many hotels will label their outlets to make sure guests know what type of power they use.  If an outlet lacks a label, this information will often be listed in the hotel services guide.  If in doubt, you should check with reception before plugging in an appliance.