pound, beat, strike, attack
扑 centers on forceful physical impact: pounding, beating, striking, or attacking with a hand or tool.
扑 combines 扌 (hand) with 卜, which likely contributes a phonetic element. The character is associated with striking or beating with the hand.
The left side is a hand 扌, and the right side 卜 looks like a stick or rod. Picture a hand holding a stick to pound or beat something.
For ボク, imagine a boxer pounding a heavy bag: the sound of a solid punch is like 'boku!' — ボク.