A pin on its own doesn't win anything, it just freezes a piece. The profit comes from what you do next: attack the pinned piece again. Since it legally cannot run away, every new attacker you add is one the defense somehow has to answer, and pawns make the cheapest, most brutal attackers of all.
So when you've pinned something, don't rush to trade it off. Ask first: can I hit it with a pawn? A pinned piece attacked by a pawn is very often simply lost, because even if it's defended, you're giving up a pawn to win a piece.
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The knight on c6 is pinned against the king by the bishop, it cannot legally move at all.
The knight can't run. Attack it with your cheapest piece.
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