My hemoglobin is 7.8. is this good or bad.

It's low: Normal range of hemoglobin for women is 12-15, so yours is quite low. At levels less than 8, many people will have some symptoms of shortness of breath or decreased exercise tolerance. Your body can get used to lower levels over time, but you should still work with your doctor to find out why it's low and to bring it up closer to normal.