What happen if I have hepatitis b surface ab (hbsab) reactive?

You're protected! Hepatitis b surface antigen means you have active virus. If your surface antigen is negative, and your surface antibody is positive, then (except in very rare circumstances) you are not infected and your antibody protection is complete. Hepatitis b surface antibody is acquired either following vaccination, or after you have cleared a past infection.
Nothing. You most likely developed immunity to hepatitis b, either from vaccination (more common) or you had the viral infection and developed antibodies to it. You should be protected from getting hepatitis b in the future.