As seen in the mnemonic, the meaning of pound here is a unit or measure of weight.
Mnemonic
[b-] Bart Simpson is in the [4] bathroom of the [-ang] chapel being forced by the 旁 sea captain to move 石 stones from one end of the tiled bathroom to the other. Only once he has moved hundreds of 磅 pounds of 石 stone will the 旁 sea captain end his punishment. Bart's crime? He stole a 磅 pound of holy bread from the priests.