Apps are made up of screens, and each one performs a different function. Screens relate to apps in the same way pages relate to books.
When you first Manage your app, you're automatically taken to the screens section.
In the above example, a fictitious Rewards app has three screens visible: New/Edit Rewards, Panel - Points (Contacts), and Rewards List.
There is also an option to create a screen, which you can read more about here.
The Reward List screen has a star beside its title. The star in the corner of the tile means this screen is the default screen that opens when a user clicks the app in the dashboard.
If you have permissions, you can change the default screen in the General section when managing the app.
Each screen also has a vertical ellipsis [
⋮ ] allowing you to manage it. For more information, please see Screen Management.