The meaning is that the eyes can say as much as the mouth. When we speak, our hands move to make our description or expression more clear or correct for the listener to understand better. Drawing a circle, describing objects, accepting or denying, assuring or puzzling, the hands keep moving as the speech or conversation goes on. While we are thinking our hands will move to our heads, shoulders, hips, or cheeks and very often they cross each other. Hands move even when we want to be calm and still.
Hands sometimes seem to be alive by themselves.
While signing, pointing, signaling and drawing our hands are busy. However, when I see a good speaker, demonstrator, or MC, their hands move objectively and purposely. Their hands are seen layered on top of each other. In kyudo practice, especially when we perform kaizoe or hadanugi or tasukisabaki, our hands express how calm or nervous our mental condition is. Hands should be subordinate to our mind and must be controlled yet, they should be enlivened.