Yoga is helpful. Anyone who has a spinal problem with benefit from exercise, especially exercises that strengthen your core muscles. Yoga is one example of an exercise that builds core strength. It will not correct or alter your scoliosis in any way, but is very helpful for reduction in back pain that may accompany scoliosis.
Exercise in general. Is beneficial for a healthy back regardless of the diagnosis with yoga an excellent way to maintain flexibility and core strength and stability. Certain poses may need to be modified if they repetitively cause pain vut they will not make the condition worse.