Can i correct my scheuermann's disease with only exercises ? is that possible? i have only 48 degree of it and im 21.

To be honest: At age 21, it would be rare that you haven't reached musculoskeletal maturity. Which mean's bracing isn't going to be of help and exercise, likewise, will not correct the physical deformity. If you have pain, exercise may help with pain. Otherwise, unless you have neurologic deficits or bothersome pain, surgery isn't routinely considered - it is also considered when there is more than 70o)