I'm sure there others on this site who could do a better job explain this.

However, as I understand it. The SR is the earth's own resonant frequency. The frequency affects us. The Power level "72" here is the amplitude and signifies how strong the resonance is. The normal 7.83 Hz frequency is the alpha/theta brainwave frequency of the human brain. The strong higher frequencies will excite peoples brain and take them out of the sleepy alpha state. Lower frequencies will create a sleepier state.

https://www.shieldyourbody.com/schumann-resonance/
https://www.drskinhealth.com/blog/schumann-resonance

Here is a list of frequencies and their supposed effect on Humans