What is exact meaning of bilateral resuidal blebs on lungs. are they harmful ?. does it cure on itself or needs doctor consultation?

It means you have blebs on your lungs. The word residual would imply that you had blebs removed and this is what is left over. If that is the case, these are unlikely to cause a problem, like a pneumothorax. But, the best doctor to evaluate this and be certain this is the case is the doctor who removed the blebs. If blebs were never removed, see a thoracic surgeon to evaluate these blebs.