A set of capabilities to ensure the right people have the right access for the right time: entitlement management (access packages), access reviews (periodic reviews), lifecycle workflows (joiner, mover, leaver), and PIM.
In SC-900 you are asked which tool to use: confirming every quarter that guests still need access → access reviews; requesting a group, an app, and a site in one step with approval and expiration → access package; removing groups and licenses on an employee's last day → lifecycle workflows.
Microsoft Entra ID Governance is a concept that can show up on the exam. Check the full guide to see it in context.