Formica, at its root, is made of paper that's been pressed together many times. Because of this, it can stain if a colored liquid sits on it too long. If you have older Formica countertops that have begun to yellow due to age, your best bet is to replace them. But with other stains, the first attempt to get them out should be plain old soap and water. Formica can scratch easily, so use a liquid soap with some warm water and let it sit on the counter for about 10 minutes before you wipe it up. You may be surprised at how much of the discoloration is on the outer surface.