This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
呤 combines 口 (mouth) with 令, which likely contributes sound. The exact historical development is uncertain.
With 口 (mouth) beside 令, imagine a mouth whispering a command, but the meaning is uncertain.
For レイ, picture a ray of light shining on the mouth 口 as it whispers a command 令: ray -> レイ.