This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
碤 combines 石 (stone) with 英, which likely contributes the sound. The exact historical development is uncertain.
The stone 石 on the left and 英 on the right suggest a type of stone or mineral, but its specific meaning is not established.
For エイ, picture a stone tablet engraved with the letter A: A -> エイ, tying the stone component to the reading.