Quality is defined as 1a: peculiar and essential character, 1b: an inherent feature, 1c: capacity or role (Meriam-Webster)
Essentially, we are talking about how “well” you can control your muscle system. As your muscle system is the sole system responsible for moving you and stopping you from being moved and the only active, and fastest adapting system responsible for absorbing and tolerating forces in all positions during all movements under a vast collection of activities, we are really speaking about how “well” you are able to generate and tolerate forces under a wide variety of circumstances.
Think about it like this: when you jump and land, it is your muscle system that needs to generate the appropriate (and ever-changing) amounts of force to get you to leave the ground as well as absorb the force when landing. Same goes for running, walking, lifting weights, swinging a golf club or tennis racquet, swimming, yoga, etc. When the quality of the control diminishes your ability to handle those situations diminishes and you can end up with pain. Sometimes it’s a little ache. Sometimes it’s back pain for 15 years. In addition to pain a whole host of other “signs or symptoms” can be present.
Motor Control Quality can affect how you feel, how it looks and how you think about how you use and move your body. Instead of trying to improve how you feel, how you look, or how you think about how you use or move your body, the answer might be to improve the quality of your motor control.