Being centered means being stable and thus being able to be of support to others.
We can use the image of a hurricane to illustrate clearly what it means to be centered. A hurricane is a cataclysmic event, it uproots trees, overthrows trucks and destroys buildings. And yet, the centre is completely calm. With all this violent movement going on, the center of the hurricane is always calm.
Being centered means staying in the eye of the hurricane. Your central position will allow you to change your viewpoint and easily observe what is happening around you, without directly being influenced by it.
Move away from the centre and you will start to feel the effects of what is happening on the outside. The more you drift away from the centre, the more you will be influenced by what happens outside of you.
Lose touch entirely with your center and you will lose all control of yourself and get completely carried away by the hurricane.