Outside that is magically available globally, not much I can add. But if you wanted to see all the methods that it has, you can do so by running Strapi via console command as follows.
yarn strapi console
Thaw will start Strapi in “interactive console” mode
Then you can type strapi and hit enter. It will spit out all methods that are available to you. A great way to explore the strapi object.
I believe it the future version of Strapi they are going to change it not to be a global object.