SEO stands for Search Engine Optimisation.
In simple terms, SEO is a digital marketing strategy that helps you rank better in Google SERP which generates more traffic to your website.
The way it works is that you make changes on and off the website to make it more attractive for search engines. Once changes are done you rankings improve. The higher you rank on the Google search results page for specific keywords you attract more traffic to the website that results in greater revenue.
There are a range of SEO strategies that are used to achieve high rankings and improve your online visibility