Bone Rhythm is a core concept taught in Z Health and I've found it to be one of the single most important teaching tools I have when it comes to getting people moving. The idea is very simple, that each bone is a rigid structure and because of that, when one end moves, the other must move.
Now, the question of how the other end moves is what matters here. When the two ends of the bone move correctly relative to each other, you have smooth, effortless movement. When they move in the wrong way, you force the joints to move improperly and your timing is off. You can apply this concept to any movement, using any bone in the body, which is a fascinating experiment, but let me start with a simple movement to illustrate the concept. Forgive me for the photos!
Here is a basic squatting action. First, the downward phase:
Then, rising up:
I encourage you to take any familiar movement and analyze it with the movement of a single bone in mind. This will often uncover stuck places in your body and you can use the right "bone rhythm" to unstick them. Have fun!