This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
匥 combines the enclosure 匚 with 弁 inside. The exact historical development is uncertain, but it likely relates to a container or box.
The outer shape 匚 looks like a box, and the inner part 弁 suggests something placed inside. Imagine a box with a lid, but its exact purpose is unclear.
For ヘン, picture a hen sitting inside a box: hen -> ヘン, and the box is the enclosure 匚.