Your brain and body working together are a biological computer of sorts. Your brain is constantly sending out electrical signals to the rest of your body in order for your body to keep functioning and carry out the tasks that it needs to.
Kinesiology is a language of acupoints and mudras that the practitioner is trained in, along with detecting small changes in muscle tone the practitioner is able to gain information from your body.
We use this information to find the source of stress being held in the body, on a subconscious level, and to release it. This allows your body's innate healing systems to kick in and return your body to homeostasis.