You see a lot of alcohol that says it is malted on the label, but what does that mean? If you were going to malt some barley you would lay out all the barley on a tarp or something. Slightly get it damp and wait for it to germinate. Once the little roots all come out you can lay it all out and dry it, as soon as it is all dry you can grind it up. Malted means you have sprouted, dried and ground up your grain. It adds another element to your product, giving it a little more complex flavors.
You could malt any type of grain that will sprout. So if a bottle says malted wheat that means they used wheat in the product. It could be corn, barley, wheat, rye and kind of grain would work. Every grain you use will leave your product with a totally different flavor. It is kind of fun to experiment with.