Why do Dharma practice often visualize lights? Lights symbolize Buddha’s career. In both exoteric and esoteric sutra, you can often see this description: when Sakyamuni Buddha is preaching sentient beings, his body glows, the lights shine into hell and so the three lower realms beings, release them from their sin, reduce their pain so they can escape from samsara.

[Excerpt from Luminous Wisdom Book Series: The Blessing of Speech]