I am assuming that you are talking about the prescription of your corrective lenses? If so, maybe this will help you understand what the number means. You didn't stat if there was a + or a - sign so I will address both. A plus sign in front of the number means you are farsighted and a minus sign means you are nearsighted. These numbers represent diopters, the unit used to measure the correction, or focusing power, of the lens your eye requires. Diopter is often abbreviated "D." For example, if your prescription says -1.00, you have one diopter of nearsightedness. This is a fairly mild amount of nearsightedness. If you are -4.25, that means you have 4 and 1/4 diopters of nearsightedness. This is more nearsighted than -1.00, and requires stronger (thicker) lenses. Similarly, +1.00 would be a small amount of farsightedness and +5 would be more. I hope this helps. Susanne