Our discussion of pins has been focused on how they can be used to capture the pinned piece. But there is another whole family of uses for a pin, equally useful and important: by pinning a piece you also render it unable to serve any defensive purpose; any pieces it formerly guarded are left unprotected or less protected. A pin thus may enable you to take material other than the pinned piece (or pinned pawn), or to gain access to squares that can lead to checkmate.
In the simple position we start with to the left, White’s queen is under attack by Black’s bishop from c8. Resist the temptation to think defensively; if possible you don't want to spend your time backing away from Black’s threats. There are two ways to instead see an offensive idea here. One is to examine any captures you can make and to inquire into the protection enjoyed by their targets. Here the most obviously contested square is f6; Black’s knight there is attacked twice, by White’s queen and by the rook behind it on f3. The knight appears to be guarded twice—but isn't: since its fellow knight on g8 is pinned, the f6 knight is protected only by its queen on b2. As the target is attacked more times than it is defended, White wins it: 1. QxN+, QxQ; 2. RxQ.
The other way to see the idea would be to follow out the lines from Black’s king and observe what might be obvious enough anyway if you were playing this position: Black’s knight on g8 is pinned. You immediately follow up with a look not only at whether the knight can be taken but at what it is supposed to protect. Here you see that the pin of the knight leaves Black’s other knight attacked twice and really protected only once.