Final answer:
Frequency is the number of waves passing a point in one second, and it is measured in hertz (Hz) or cycles per second.
Step-by-step explanation:
The frequency of a wave is the number of waves passing a point in one second. It is measured in hertz (Hz) or cycles per second. The SI unit for frequency is hertz (Hz) or s⁻¹. For example, if a wave has a frequency of 10 Hz, it means that 10 wave cycles pass by a point in one second.