This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
捃 combines 扌 (hand) with 君, which likely contributes the sound. The exact historical development is uncertain.
The hand radical 扌 beside 君 suggests an action, but the meaning is unclear. Imagine a hand doing something with a ruler (君 can mean ruler), but treat the meaning as uncertain.
For クン, imagine a hand (扌) picking up a kun reading book: kun -> クン.