This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
硌 combines 石 (stone) with 各, which likely contributes a phonetic element. The exact historical development is uncertain.
The left side is stone 石, and the right side is 各. Without a clear meaning, picture a stone with a distinctive mark, like a label 各 carved into it, but its purpose remains a mystery.
For ラク, imagine a lucky stone: luck -> ラク, and the stone 石 on the left is your lucky charm.
—