He is Allah, beside Whom La ilaha illa Huwa, the All-Knower of the unseen and the seen. He is the Most Gracious, the Most Merciful.
Allah states that He Alone is worthy of worship, there is no Lord or God for the existence, except Him. All that is being worshipped instead of Allah are false deities.
Allah is the All-Knower in the unseen and the seen, He knows all that pertains to the creations that we see, and those we cannot see. Nothing in heaven or on earth ever escapes His knowledge, no matter how great or insignificant, big or small, including ants in darkness.
Allah's statement,
هُوَ الرَّحْمَنُ الرَّحِيم
(He is the Most Gracious, the Most Merciful). was duly explained before at the very beginning of this Tafsir, so it is not necessary to repeat it here, and it asserts that Allah is the Owner of the wide encompassing mercy that entails all of His creation. He is Ar-Rahman and Ar-Rahim of this life and the Hereafter.
Allah the Exalted said in other Ayat,
وَرَحْمَتِى وَسِعَتْ كُلَّ شَىْءٍ
And My mercy embraces all things. (7:156),
and,
كَتَبَ رَبُّكُمْ عَلَى نَفْسِهِ الرَّحْمَةَ
Your Lord has written (prescribed) mercy for Himself. (6:54),
and,
قُلْ بِفَضْلِ اللَّهِ وَبِرَحْمَتِهِ فَبِذَلِكَ فَلْيَفْرَحُواْ هُوَ خَيْرٌ مِّمَّا يَجْمَعُونَ
Say: "In the bounty of Allah, and in His mercy; -- therein let them rejoice." That is better than what (the wealth) they amass. (10:58)
Allah the Exalted said,