This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development is uncertain. The character combines 足 (foot) with 春, but the original semantic and phonetic roles are unclear.
The left side is 足 (foot) and the right side is 春 (spring). Imagine a foot stepping awkwardly in spring mud, but the meaning is uncertain.
For シュン, imagine a foot stepping on a shun (シュン) vegetable in spring: the foot 足 steps on a spring 春 vegetable, and the sound is シュン.