To repeat our current theme: When you see a pin of any sort, consider two ways of exploiting it: by attacking the pinned piece or by going after whatever it protects. In this case, for example, you see the pieces lined up on the b-file and realize that White has a relative pin on Black’s bishop. The pin creates a pair of potentially vulnerable targets for White to consider: the bishop (because it is paralyzed) and the rook on c3 (because it is left loose by the pin). There are, in turn, two general ways to attack a loose target: by piling up more attackers against it than your opponent can counter with defenders (but it's hard to win a piece this way unless it's paralyzed); or by making it the subject of a fork. The idea behind the fork is that you throw an attacker at the target and at the enemy king simultaneously. Your opponent then has no time to add a defender to the target to offset your attack, as he is too busy moving the other piece—hopefully his king.
In this case the workable target is the Black rook, and the preferred method of taking it is a fork. Your queen is available, so your first thought is to find a square from which it can attack the rook and Black's king at the same time. If no such square yet exists, maybe you can make one by playing with checks that force Black to move his king and allow you to move your queen around, too. Thus you consider Qe8+; this forces Kg7. Now you follow up with the fork Qe5+ and take the rook next move.
The natural result you might visualize after you take the rook is Black's reply BxQ, after which you play RxQ and have won the exchange. But actually Black can do a little better; after White’s QxR, Black plays Qxg2+, picking up a pawn. (Black's queen was going to be lost anyway, so he might as well try to take something with it.) White responds KxQ, and then Black still has BxQ. The sequence nevertheless remains worthwhile for White, as a rook is much more valuable in the endgame than a bishop that can only patrol squares of one color.
This position has more to do with building a queen fork than with pins; but what makes it go is the observation in the first place that Black has a loose rook worth forking—and this because his bishop is laboring under a relative pin. The position thus is a good example of how a pin and fork can work together. It also shows yet again the value of having a look at any checks you can give. Even if you overlooked all other patterns at the start of this position, looking for checks and finding Qe8 (and then the next check—the queen fork Qe5) would have led you in the same direction.