You have sun light. What kind of light would this be? Obviously sunlight.
This is a jukugo word, which usually means on'yomi readings from the kanji. Since the にち reading of 日 becomes にっ here, we've made a mnemonic for you to remember this reading:
The best place for sunlight in Japan is Nikkō (にっこう). It's one of Japan's most beautiful national parks, and the perfect spot to catch some rays!
Bathing too long in the sunlight isn’t good for your body.
I'm being as careful as possible to not get exposed to direct sunlight.
Seeing sunlight always makes me sneeze for some reason.