This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
皪 combines 白 (white) with 樂, but the exact historical development and original meaning are uncertain.
The left side is white 白, and the right side is 樂 (music/comfort). Picture a white musical note, but the meaning remains unclear.
For レキ, imagine a white lake (レキ sounds like 'lake') reflecting music: lake -> レキ.