AOAG stands for [Always On Availability Group].

The primary use of [AOAG] is to synchronize multiple SQL Server instances into a failover-safe environment. All other members are updated when the primary server is updated, so each member is ready if it is set as the primary. Only the primary instance is used at any given time and can remain the primary for as long as needed, until it fails over to another member.

The following script checks whether all members have the proper settings for safe failover when required.

select ag.name
   ,  ar.replica_server_name
   ,  ar.availability_mode_desc
   ,  ar.failover_mode
   from sys.availability_groups ag
   inner join sys.availability_replicas ar
      on ar.group_id =  ag.group_id

The output will be similar to this example.