This rare kanji has no clear standalone meaning. Its meaning is uncertain, but it is associated with the beautiful light of the moon based on its reading.
朎 combines 月 (moon) with 令, which likely contributes the sound. The exact historical development is uncertain.
The moon 月 on the left and 令 on the right suggest a connection to moonlight. Think of the moon's beautiful light shining through a clear night.
For レイ, imagine a ray of moonlight: ray -> レイ, and the moon 月 shines beautifully.