Talaq al ba'in means irrevocable divorce.
Talaq is the Arabic word for divorce, and al ba'in refers to the type of divorce that is considered to be final and cannot be undone. This type of divorce is usually only used in extreme circumstances and is considered to be the most serious form of divorce in Islamic law. Once a couple has undergone talaq al ba'in, they are no longer considered to be married and cannot reconcile without undergoing a new marriage ceremony.