How does arbitration resolve an unresolved labor grievance?

"If the problem isn’t solved, the grievance is put in writing. The employee, one or more union officials, the supervisor, and perhaps the plant manager then discuss the grievance. If the matter still can’t be resolved, another meeting takes place with higher-level representatives of both parties present. If top management and the local union president can’t resolve the grievance, it goes to arbitration. Arbitration is the process of settling a labor-management dispute by having a third party—a single arbitrator or a panel—make a decision. The decision is final and binding on the union and employer. The arbitrator reviews the grievance at a hearing and then makes the decision, which is presented in a document called the award. In the one-day suspension mentioned above, the arbitrator might rule that the discipline was improperly made because the employee’s attendance record for the month was not accurately maintained by the firm."