G-d knows Himself. His self-knowledge is infinite because He is infinite. This self-knowledge is called, Ohr Ein Sof (The Infinite Light). Though this self-knowledge reveals the essence of G-d, it itself, is not the essence of who He is, but is rather His infinite revelation. Nonetheless, it is not outside of Him, but is, rather, the revelation of Himself to Himself.
This can be further understood by the statement, “Before the creation of the world, there was He and His name alone.” (Pirke D’Rabbi Elazar, Chapter 3). The word “He” refers to G-d Himself and “His name” refers to the Infinite Light, the revelation of Himself. The effect of a name is that it draws out and reveals the identity of the one being called. When a person is called by name, it draws out his essential self, his identity, so that his attention is turned toward the caller. Furthermore, a name identifies that which is called by it. However, a name is not the thing itself, it only brings to light the identity of the thing named. Another similar aspect of a name is what the Tanach states in regard to King David, that he, “Made a name for himself”. This is to say that he became well known. Likewise, in reference to G-d, “His name” means His self-knowledge. G-d knows Himself and, so to speak, this is how He would identify Himself. This may be discerned from the tetragrameton, the four letter proper name of G-d. This name, Y-H-V-H, is made up of the three letter root, HVH, which means, “To be”, plus the prefix Y, which modifies the verb and makes it a constant. The name Y-H-V-H therefore means, “The true Being, who was, is and will be, at once, and is the source of all being”. This is to say that it is the infinite revelation of G-d Himself. Since the Ohr Ein Sof is the revelation of G-d, as He truly is, therefore it bears all his properties. Just as He is a simple quintessential singularity with no parts, so is his light. Conversely, just as He is Kol Yachol, that is, He has infinite abilities (Heyulies), so does his light.
