There are two options used to allow access to your app: Permissions and Rights.
Permissions: This allows you to set permissions on the app itself.
You can grant users the ability to access, manage, and customize your custom app, as well as the app's Rights as explained in the next point.
Right: This allows you to set permissions on the records the app manages.
These are disabled by default and do not even have any out-of-the-box functionality when enabled. A customizer will have to define what each Right means within the app itself.
For more information on what each permission does, please see Permissions and Rights.