Explanation

Box 1: Contact
With Contact scope, a signed-in user in the role for which the permission record is defined will have the rights granted by that permission only for records that are related to that user's contact record via a defined relationship.
Box 2: Account
With Account Scope, a signed-in user in the role for which the permission record is defined will have the rights granted by that permission only for records that are related to that user's parent account record via a defined relationship.
This scope means that the entity list will only show the records of the selected entity that are associated to the user's parent account. For example, if an entity permission allows Read access to Lead entity with the Account scope, the user having this permission can view all the leads of only the parent account of the user.
Reference:
https://docs.microsoft.com/en-us/powerapps/maker/portals/configure/assign-entity-permissions