This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
瑃 combines 王 (jade/jewel) with 春 (spring), suggesting a type of jade or gemstone associated with spring. The exact historical development is uncertain.
The left side 王 suggests a jewel, and the right side 春 suggests spring. Imagine a rare spring-green gemstone, but remember its meaning is uncertain.
For チュン, imagine a spring jewel that makes a soft 'chun' sound when tapped: chun -> チュン.