Answer:
Frequency means 'how many times an event happens in a period of time'.
Most things have a resonant frequency. This is that they will vibrate, or wobble, in a reular pattern, when stimulated by an external force. The frequency of natural resonance will depend on the material and size of the object.
The frequency of electromagnetic fields is known as radio. The infinate number of different frequencies, enables us to choose one signal over another, by use of resonant circuits and filters.
The resonant frequency of taught strings and columns of air, gives us musical instruments. The regular movement of changes in air pressure, enables us to percieve sound at different frequencies.
So, just about everything has a 'Frequency'