What exactly is Nano coating?

Nano coating is the name of a colorless liquid water-based impregnation agent that is highly water-repellent.

It coats the wood fiber and absorbs into the wood. But it does not form a layer on the wood, you cannot see it. If you pour water over it, it will roll off. The wood can continue to breathe and water can get out of the wood but not into the wood. You have to pay close attention to this when purchasing a product. (Paint, for example, that closes the wood. But if the wood was not dry properly, for example, it will rot further under the paint layer.)