This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
皢 combines 白 (white) with 堯, which likely contributes a phonetic element. The exact historical development is uncertain.
The left side 白 suggests whiteness or brightness. The right side 堯 is tall and layered, like a high mountain catching the first light. Together they hint at something becoming clear or bright.
For キョウ, imagine a bright white light shining over a tall mountain, and a voice echoes 'kyou' (今日, today) as the day becomes clear: kyou -> キョウ.