Revenue per click is simply the average revenue for each individual click on all of your pay-per-click keywords and ads. [1]
[1] (2017, December 01). 2 Key Formulas for Understanding Your PPC Data | DMI. Retrieved May 21, 2021, from https://digitalmarketinginstitute.com/blog/2-key-formulas-for-understanding-your-ppc-data
[2] Using 'Revenue-per-click' in Google Analytics to Assess the Effectiveness of your AdWords Campaign - Gravytrain. Retrieved May 21, 2021, from https://www.gravytrain.co.uk/blog/revenue-per-click-for-adwords-campaigns/