"CC" stands for cubic centimeters when pertaining to engines. This is a measure of the engine's displacement, or the total amount of air and fuel mixture an engine can pull in across all cylinders.
An engine's displacement is determined by finding the volume of one cylinder using its stroke and bore, and multiplying the resulting number by the total number of cylinders. The displacement is important for a number of reasons, notably the fact that it is used in many countries as a method of determining a vehicle's rate of taxation. In the United States, engine displacement is expressed in liters, which is equal to the displacement in cubic centimeters divided by 1000.