An executor is a person appointed by the deceased to manage their estate after they have passed away. The executor shall apply to the court for a Grant of Probate in order to administer and distribute the deceased’s assets to the beneficiaries specified in the will.
If no valid will is available then the court will appoint a person who is suitable to manage the deceased's estate, usually following the Intestate Succession Act. In this scenario, you would apply for a Grant of Letters of Administration rather than a Grant of Probate.