To be answerable for the results of an assigned action.
Accountability is associated with delegated authority and is distinct from responsibility.
To sanction or officially confirm that a transaction is appropriate. Approving is the technical step done by the transaction processor after they have received appropriate authorization. The approver checks that the authorization is valid, funds are available and being used for an appropriate item, policies are followed, etc. One can only approve with authorization. A separation of duties is implied by the authorization and approval process.