That's right. It's a program that allows you to edit your savegames so you can change global variables, but more importantly, it allows you to give the characters in your party a makeover. Shadowkeeper allows you to change your characters' appearance, his or her stats (and if it IS a he or she in the first place), resistances, class, experience level, movement speed and so on. It also allows you to edit spell lists, so your character can suddenly know spells he or she never knew before.
The best used part is the bit that lets you edit a characters inventory. It comes with a full list of the items in the game, and you can get your character any one of them. When you load the savegame he/she could suddenly be carrying a mighty sword, a certain key or a burning hands scroll.
Unless you've got good reason to use it (if you lost an item critical to a quest or you're trying to create a unique character class for example) it's cheating, but noone but yourself should care.
You can download it
over here. You can also get similar programs for games like BG1 and Icewind Dale.