hand, hand radical (no. 64)
扌 is the hand radical, used as a component in other kanji to indicate actions done with the hand. It does not function as a standalone character.
扌 is a simplified radical form of 手 (hand), used when 手 appears as a left-side component. The three strokes represent a stylized hand.
The three strokes look like a hand with fingers extended downward, ready to grasp or act. Think of it as the hand that does work in many action kanji.
For シュ, imagine a hand making a shoe: the hand radical 扌 crafts a shoe, and shoe -> シュ.
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