Body knowledge is a term used when it’s more than just our brain, or mind which knows a thing. It’s when the body knows it too. When the body knows it better.
When we practice something over and over again, It is ingrained deep within us. In learning a Tai Chi or Kung Fu move, for instance, it is our bodies which learns. It is our bodies which performs.
Our mind needs to be engaged to initially remember the move though. The mind starts in the drivers seat, performing what was just learned. However, over time the mind takes a back seat and lets the body drive.
Due to the repetitive practice of the body, the body knows how to perform the task learned better than the mind can imagine or direct the body. The body then becomes the driving point for the applying this knowledge.
When we know the form this way, we don’t think about it, we will just do it.
From a martial art perspective, thinking about what to do (during a fight), will only slow your reaction time down. We need to respond to what our opponent is doing instantly, without thought. Body knowledge gives us this.