The nine shapes in the BodyGraph are the Head, Ajna, Throat, G, Heart, Solar Plexus, Sacral, Spleen and Root. Each one governs a particular kind of pressure, awareness or energy, and each one is either coloured in or left white.
A coloured center is consistent. You can count on it, other people can count on it, and it is part of what you reliably bring to a room. A white center is where you take in the people around you and turn the volume up on what they are carrying. That is worth saying plainly, because almost everyone reads white as missing: an open center is not a deficiency and it does not need fixing. It is where you are most impressionable, and over time it is where you become genuinely wise, because you have felt that particular thing in hundreds of different people rather than only in yourself.
The catch is that an open center is also where you are most easily talked into a life that is not yours. Someone with an open Sacral can spend years working past the point their body wanted to stop. Someone with an open Solar Plexus can spend years avoiding an honest conversation. Knowing which of your centers are open is usually the moment a chart stops being interesting and starts being useful.