Here's a breakdown:

* Frequency is measured in Hertz (Hz). One Hertz means that one complete wave cycle occurs every second.

* Higher frequency means more cycles per second - the wave oscillates faster.

* Lower frequency means fewer cycles per second - the wave oscillates slower.

Think of it like this:

* Imagine a bouncing ball. A high frequency is like a ball bouncing rapidly, whereas a low frequency is like a ball bouncing slowly.

* Sound waves: High frequency sounds are higher pitched (like a whistle), while low frequency sounds are lower pitched (like a bass drum).

* Light waves: High frequency light waves are closer to the violet end of the spectrum, while low frequency light waves are closer to the red end of the spectrum.

In short, the frequency of a wave tells us how fast it is oscillating or repeating itself.