Staging is the presentation of an idea so that it is completely and unmistakably clear.
An action is staged so that it is understood. To stage an idea clearly, the audience's eye must be led to exactly where it needs to be at the right moment. It is important that when staging an action, that only one idea be seen by the audience at a time.
For example, in a scene with plenty of action, the audience's eye will be drawn to an object at rest. Conversely, in a still shot, the eye will be drawn to the item in motion. The animator is saying, in effect, "Look at this, now look at this, and now look at this."
A personality is staged so that it is recognizable; an expression so that it can be seen;. A shy child would turn their eyes down, and slightly rotate their upper body away for the gaze of another child. The child's actions reveal the fact that he is shy. When staging a personality, it is useful to use characteristics that clearly define the character.
A mood is staged so that it will affect the audience. The tight composition of dark trees in a dense forest, leaning in toward a scared youth; eyes glowing from within the thick; hurried breathing filling the air; the childs eye wide open. All of these elements have been clearly staged to inspire fear.