A vehicle always gets its power from its engine. Engine Capacity/power is also known Engine Displacement which is often seen with a CC attached to it. So, what is CC?
The engine consists of a cylinder where the fuel and air are trapped inside. There may be multiple cylinders depending upon the engine type (single-cylinder engine, double cylinder engine, etc.). Each cylinder has a piston inside it that moves up and down compressing the fuel-air mixture which will keep it moving. The moving pistol results in the rotation of the wheel.
The bigger CC engine has a bigger space (volume) available inside the cylinder to accommodate air-fuel mixture for burning. The greater volume of the engine sucks more air and fuel into the cylinder. The more amount of fuel burning results in higher power output because of the powerful movement of the piston inside the cylinder that will produce higher torque.
Hence, in simple words, the powerful engines are massive in shape and size. Similarly, supplying more fuel to the engine, on the other hand, reduces the mileage of the vehicle because of the increased fuel consumption.