An order to exonerate bail/bond is basically an order to “free/clear” the money or property put up as bond money, and return it to the person who posted it. It can happen after a trial is completed by either the charges dealt with and no longer needing to attend court, or it could have been the case of somebody who placed the bond has revoked it, and the person charged is now back in custody awaiting trial.
Simply put, release the money.