I am experience brown discharge on second week of the pill (necon), what is it?

Normal adjustment: When on oral contraception, it's not unusual to have brownish discharge or even spotting as the uterus adjusts to the hormones in the pill. This is called breakthrough bleed and should resolve with time. Keep on your regimine, don't skip pills and try to take the pills the same time each day. That will help provide a more stable environment for your uterus.