I am making burboun chicken and i am wondering how much 2 slice's of ginger =?
Rely on your good judgment. Just slice it from a ginger root, not too thick, not too thin.
Slices of ginger are usually described as the size of a quarter, if that helps. But you have leeway in the amounts when you are cooking. A little more or less rarely makes a crucial difference. Note that I am talking about cooking, not baking. In baking, you need to follow measurements precisely until you know a bit about the rules.
As you probably know, a ginger root is not symmetrical, so it depends on your taste. My wife love ginger, so she would probably make a nice, long vertical slice about an 1/8 inch thick. I just like a hint, so I would make smaller slices horizontally. I wouldn't stress that much, if it's only 2 slices, it's not going to ruin the dish either way. Or you could get a jar of pre-sliced ginger, but what's the fun in that.