The word Nur is Arabic for light, in one sense it can mean that God illuminates the world with understanding. The scholar Abu Bakr ibn Arabi categorized nūr into different levels of understanding from the most profound to the most mundane. From here i am taking the esoteric understanding (Sufi).
Nur is the first creation of God and everything else, came from it according to Sufi mysticism. The Sufi theoretician Fariduddin Attar wrote , (c. 1145–1221) wrote, “The origin of the soul is the absolute light, nothing else. That means it was the light of the messenger, nothing else. Ibn Arabia, taught there was three types of light, Nur Al anwar (Light of lights), Anwar al mani (the light of the intellect) and Anwar al tabia (the light of nature). Also Inayat Khan (1882 – 1927) wrote , “The soul is like a ray of the sun. The angels, who do not have physical bodies, are made of nūr, or light, that comes from the divine Sun, the Spirit of God. All souls are made of Nur, or contain some part of that essence, which is the essence of the whole manifestation.”
The light here on a esoteric sense refers to the light on the border of dreaming, (Astral world), that is just before dreamless sleep (Ain Sof). It is not uncommon when one sees flashes of this light to see a high guru or prophet or to hear voices but mentally see no forms.