To understand the application I would start to have a look at the navigation and see where you get to the different pages and how they are interconnected. You can find all pages by performing a advanced search in Mendix Studio Pro, but there is no page flow function available. There is however lots of things possible from the context menu for example you can discover lots about usage and pages and microflows that are connected.
To learn more about Mendix, visit the academy online and maybe stat out with this learning path: https://academy.mendix.com/link/path/40/Mendix-Basics