Here are some nouns that describe light, categorized for easier understanding:

General Light:

* Light

* Illumination

* Radiance

* Luminescence

* Brightness

* Glow

* Sheen

* Sparkle

* Flare

* Beam

Specific Types of Light:

* Sunlight

* Moonlight

* Firelight

* Starlight

* Lamplight

* Neon

* Phosphorescence

* Fluorescence

* Laser light

Metaphorical Light:

* Hope

* Enlightenment

* Knowledge

* Inspiration

* Clarity

* Vision

Scientific/Technical:

* Photon

* Wave

* Ray

* Spectrum

* Wavelength

* Frequency

Other:

* Flash

* Glimmer

* Blaze

* Gleam

* Aura

* Halo

This list isn't exhaustive, but it gives you a good starting point for describing light. The best noun to use will depend on the specific context and the feeling you want to evoke.