Azure AD reviews are a capability provided with Azure AD P2 licenses that allow you to automate the discovery and access control of user account in Azure AD groups and roles. This video give you a walk through of the basics of creating and using access reviews to ensure your environment remains secure.
You can find the video here – https://www.youtube.com/watch?v=UxlVuSNBBzE
You can learn about Azure AD access review here:
CIAOPS 