We learned how to define a navigation structure using Xamarin.Forms Shell, how to navigate to views using routes, and how to pass arguments between views in the form of a query string. There is a lot more to Shell, but this should get you started and confident enough to start exploring the Shell APIs. Also keep in mind that the Shell APIs are constantly evolving so make sure to check out the latest features available.
We also learned how to create an API client to an arbitrary REST API, which always comes in handy since most of the apps you will write need to communicate with a server at some point. There is a very good chance that the server will expose its data and functionality through a REST API.
The next project will be about creating a match-making app, and how to create your own swiping enabled Yes/No image selector app, using nothing but Xamarin Forms to render and animate cross-platform UI controls.