This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
黬 combines 黑 (black) with 咸, which likely contributes the sound. The exact historical development is uncertain.
The left side 黑 means black, and the right side 咸 looks like a container. Imagine a pot of black soot or ink, but the exact meaning is unclear.
For カン, imagine a can of black paint: can -> カン, and the kanji has 黑 (black) on the left.