Re: capacitance loading
It means that this "driver" can charge and discharge a capacitance in requested period of time, which is usually very, very short ..
A mosfet transistor is a good example of capacitive load. If you want the rising and falling edges of an impulse to be very sharp you have to ensure that a driver connected to the mosfet's gate can within nanoseconds charge or dischrge the capacitive load of the gate. Longer switching time - more energy wasted as heat..