An Azure SQL Database/Managed Instance feature that manages replication and automatic or manual failover of a set of databases to a secondary region, exposing listener endpoints that stay the same after a failover.
On AZ-305 this is the recommended business continuity (BCDR) solution for Azure SQL when automatic failover is needed without changing the application's connection string. It differs from manual active geo-replication in that it manages failover transparently.
Auto-failover Groups is a concept that can show up on the exam. Check the full guide to see it in context.