Carb cycling means consuming a different amount of carbs each day, on a "cycle", in order to balance out the weight loss benefits of a low carb diet while also revving your metabolism and keeping your energy levels up with higher carbs. For example: Monday you eat 200g of carbs; Tuesday you eat 100g; Wednesday you have 50g; Thursday you start the 3-day cycle over again.
This is actually the carb cycle I used pre-contest for my first bodybuilding competition January-April. It is not easy -- especially the low carb days. But it does work. Stick to low-glycemic index, complex carbs: oatmeal, long-grain brown rice, quinoa, sweet potatoes. Keep your protein high: a gram and a half a day per pound of bodyweight.