It's easy to picture a pitch shot when it is contrasted with the chip shot. A chip shot is usually played from closer to the green and the ball is in the air only a short amount of time; the point is to get the ball onto the surface of the green and let it roll toward the cup. Most of a chip shot is roll. A pitch shot, on the other hand, is in the air for most of its distance, with much less roll once it hits the ground; a pitch shot also goes much higher in the air than a chip shot.
Pitch shots are played with wedges - one of the clubs in a set of irons is called a "pitching wedge" because it was originally designed for this shot. But other wedges - gap wedge, sand wedge, lob wedge (all of which have higher lofts than a pitching wedge) - are also used for hitting pitches.
Generally, if you have the option of hitting a chip shot or a pitch shot, it's best for most golfers to go with a chip (see "Favor chipping over pitching when possible"). But you don't always have an option. When you need to get the ball up in the air quickly; when there is rough or other problem areas between you and green and therefore roll is not possible; or when you want the ball to come down with a steep angle of descent and therefore hit the green without much roll, a pitch shot is appropriate.
Also see:
For pitch shots, try the 7-8-9 method
My pitch shots haven't been landing soft enough lately, so I'm going to the practice area to work on my pitching.
