It means that if you are so busy running your mouth you are not doing anything or getting anything done. I would like to point out that this is far from true. Often our best orators are also people who get things done. Examples you say? Martin Luther King Jr., Churchill, Lincoln, Jesus, Socrates, and any great teacher you have ever had just to name a few; all had significant impacts on the world using there words.
Yes you are so right about that...
It just means that some people can maybe talk a good argument, but that's all they do, they don't take actions to follow up what they are saying...