There are two types of Cuban currency: the “CUP”, exclusively used by the Nationals, and the the Cuban Convertible Peso, known as the “CUC”. Basically, all goods and services a tourist pays for will be made using CUCs. There are roughly 25 CUPs to 1 CUC, but you will most likely not see a CUP during your visit here!
The CUC is what you will be exchanging your USD to and using while in country for all spending needs. This exchange rate is "upside down" as it is currently 100/88. In example when you change $100 USD you will receive $88 CUC.