the quartz crystal inside a watch needs energy to spark it to vibrate at a given frequency, thereby creating ‘the heartbeat’ to measure time.
the same is true for computers, hence the ‘Hz’ rating.
‘Hz’ stands for Hertz and is the SI unit for frequency. It is the last name of Heinrich Hertz; a physicist who demonstrated that Maxwell’s theory of electromagnetism is correct. Electromagnetic waves were called Hertzian waves and, later, radio waves.