In America, if you want to gesture to someone, "No", or not to do something, particularly to children, we wave our index finger back and forth. In Japan, they wave the whole hand back and forth in the same meaning, but it is used in many more situations. It is used to mean a negative response to a question like, "No, it wasn't me.", "I didn't do that.", or "That's wrong." It's a very common gesture used with adults, not just used to scold children.