RF are waves of electrical impulses that oscillate at very high frequencies. The waves are no different than our 50 cycle or 60 cycle line voltages and currents. Instead of having 50 or 60 cycles occurring every second you can have billions occurring every second. A frequency of 1 GHz is a frequency that is oscillating at 1 billion times every second. In the digital world electrical pulses pass along information. The shorter the pulses the more one can pass added information every second. A computer operating at 2 GHz is capable of processing 2 billion pulses every second. For electronic circuits to process a pulse it has to have the ability to carry 5 times its base. This means that the circuits carrying 2 GHz pulses need to have the capability of carrying 5 times that or 10 GHz on an RF basis. This is because square waves are made of 5 harmonics of the original frequency.