In the 'Maintain Business Roles' SAP Fiori app, key activities include assigning business catalogs to a business role and maintaining restrictions. Business catalogs, which group together Fiori apps and other resources based on business functions, can be linked to business roles to define the set of apps and actions a user with that role can access. Additionally, setting restrictions within a business role allows for further refinement of what users can see or do within the apps, tailoring access to the specific needs and security requirements of the organization.
References:
SAP Fiori Administration Guide
SAP S/4HANA Cloud security and role management documentation