Sounds like you have two single-coil pickups and one humbucker. The single coils are at the neck and in the middle, and the humbucker is at the bridge.

The humbucker is, roughly speaking, two single coils wired together in such a way that any "noise" picked up by one is cancelled out by the other.

Single coils tend to be better for clean playing, and humbuckers [/i]tend[/i] to be better for playing with distortion, but that's by no means a hard-and-fast rule.