Ok i downloaded and installed this plug-in (btw i am running Gimp 2.6.8 on Win XP Pro).
The description from the plug-in registry pretty much tells you what this plug-in does.
It swaps one color for another. It is a quick way to do a color change kinda. It is a pretty cool plug-in, but the color change can effect the whole tone of the image and to really achive a color swap you would also have to employ a layer mask.
The source color is the one you want to change. The target color is the color you are swapping the source for.
Say you make your source Yellow and you target Blue. Now where ever there is yellow it will be replaced with blue.
