This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
旾 is a rare variant form. It visually combines 屯 (top) and 日 (bottom), but the exact historical development is uncertain.
The top 屯 and bottom 日 suggest a connection to spring or a seasonal idea, but the exact meaning is unclear.
For シュン, imagine a rare spring flower named Shun blooming under the sun 日: Shun -> シュン.