There are three planes in which the body can move in frontal sagittal and transverse. The frontal plane is the plane in which your body moves side to side imagine if there is a mirror or a wall behind you cutting your body in half anything side to side is the frontal plane. The sagittal plane is the plane in which the body moves front to back so imagine if a wall or a mere was going straight through your body right down the center anything going forward and backward is the motion for sagittal plane. The transverse plane is the plane in which your body rotates off of a pivot imagine A piece of wall are glass going straight through the center of the body horizontally any rotation of the upper body the lower extremities the shoulders external or internal are the transverse plane. We typically hit all three planes to balance the body the frontal plane is the least work plane sagittal is the most work plane and transverse is also one of the least worked planes. The order in which exercise you use depends on the dysfunction of the client but typically we like to go frontal first sagittal second and transverse third easy way to remember the order is f for frontal f is also first s for second s is also sagittal and T for transverse T is also third.
Knowing which plane to move through can greatly assist a client to reach their goal whether that is getting rid of pain getting stronger realignment. Most people do not use the correct planes when trying to "fix" a dysfunction. For example if someone has a tight chest typically they do a row which is in the sagittal plane this main strengthen the rhomboids who assist the chest in opening but the real plane to be worked is the frontal plane to allow the chest to fully lengthen through a full range of motion while keeping the scapula and rhomboids engaged