Overall mobility, also known as Structural Balance is how balanced and mobile your entire body is as a whole. Structural balance is by far the most important thing you need for growth, health and injury-prevention. A balanced body that is mobile everywhere is almost bulletproof to injuries because it doesn't have any weak links to it. A good level of structural balance allows the individual to perform and handle any postures and positions the body is put into. Also, because everything is working correctly, no joint is getting too much unnecessary strain which helps to prevent many chronic injuries people experience. Your body wants to maintain balance by default. It's basically the body's injury prevention mechanism. You will not be able to grow to your full potential without structural balance, because the body will restrict your growth in order to stay healthy and to prevent injuries.
How to Build Mobility
Using the full range of motion with compound exercises Compound exercises are big multi-joint exercises like push ups, pull ups, bench press, squats and deadlifts. You will develop good levels of mobility by doing big compound exercises with a full range of motion. This means that you will squat all the way down. You will start the pull ups from straight arms and then pull up to your chest. You need to be in control of the range of motion, just doing the full range of motion won't be enough (swinging, twerking etc.). Many people, mostly bodybuilders, use only a small portion of the range of motion which merely builds strength in that small range of motion. You want to build strength in the entire range of motion.