This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
皣 is a rare character composed of 白 (white) and 華 (flower/splendor). The exact historical development is uncertain, but it likely relates to brightness or whiteness associated with flowers.
With no clear meaning, picture a white (白) flower (華) as a placeholder: 皣 might suggest something pale and floral, but its true sense is unknown.
For ヨウ, imagine a white flower glowing with a soft 'yo' sound: yo -> ヨウ, like the beginning of 'yonder' light.