Brightness
Splendor
noun
The light's radiance is that of brightness and splendor.
光輝 can refer to both physical radiance or to the metaphorical brilliance of someone's achievements. It's a formal word used mostly in advanced written contexts, but you may also come across it as a name (usually for males) in everyday life.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
彼は光輝燦然と旗を掲げました。
He raised the flag in all its splendor.