@SCB21 See https://experienceleague.adobe.com/docs/audience-manager/user-guide/features/data-sources/datasource...
Share Enabled: Your data source can be shared with other partners
Suggestion: I believe in case you want to use this data source in the AAM Marketplace
Share associated visitor or device IDs across the Audience Manager Platform
Your data source contains visitor or device IDs that can be shared across other Experience Cloud solutions.
Suggestion: I'm thinking about an AAM - Target workflow for instance