Explanation

Box 1: Privileges
Privileges: This defines whether a subarea is displayed based on privileges available in any security roles that are assigned to the user.
Box 2: SKU
SKUs: Select the versions of Dynamics 365 that display this subarea.
Box 3: Client
Client: Select the type of client that displays this subarea.
Reference:
https://docs.microsoft.com/en-us/powerapps/maker/model-driven-apps/create-site-map-app