Do you mean polycystic ovarian syndrome?
If so, generally that means you are not ovulating or not ovulating regularly/predictably. By taking clomid near the beginning of your cycle (differen doctors use different cycle days) it is hoped that will stimulate your ovaries to ovulate that cycle. It doesn't work for every woman or every cycle & a lot of women find they need to try different doses before they get the right one or combine the clomid with other therapies (other meds, diet, exercise, etc.)
Hope that helps a little.