This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
灥 is a triplication of 泉 (spring, fountain), likely intended to represent many springs or abundant water. The exact historical development is uncertain.
Three springs 泉 stacked together suggest many springs or abundant water flowing from multiple sources.
For シュン, imagine a rushing sound of many springs: shun-shun-shun, like water gushing from three 泉. The shun sound cues シュン.