Nicola Tesla said if you wish to understand the Universe, then think of Energy, Frequency and Vibration.
Everything has a vibrating frequency, which is called resonant frequency.
This can be explained using an analogy of an opera singer who uses their voice to shatter a crystal glass. The glass is vibrating at a certain frequency, and when the opera singer sings at that particular frequency the glass shatters.
In the same way, each microorganism has a unique and specific frequency (or vibrational rate). When you add MORE OF THIS SAME frequency to the microorganism, it cannot tolerate it, and it bursts or dies. Rife machines generate resonance waves which destroy harmful bacteria without doing any harm to the users.