بِسْمِ اللهِ الرَّحْمٰنِ الرَّحِيْم
Al-Awwal means there was nothing before Him and everything other than Him are brought int existence from absolutely nothing. While Al-Aakhir means there is nothing after Him. He is infinite and will exist for all eternity.
Both words occurred once in The Qur’an, “He is The First and The Last, The Outward and The Inward; and He has full knowledge of all things.” (Surat Al-Hadeed, 57:3)