What are good foods for a diabetic to eat?

It varies. A healthy well-balanced diet, 3 meals without snacks. Caloric restriction if you need to lose weight. There's no magic here. Find an eating plan you can follow the rest of your life, not a short-term diet. Check w/your registered dietitian.
Low glycemic foods. The best foods are those that are low glycemic index, or those that release sugar more slowly to the bloodstream, together with low fat and low sodium foods. Whole grains are always lower glycemic index than processed foods, and most vegetables and many fruits are good, but best to see a nutritionist and your provider for a good, balanced diet including lots of physical activity, if possible.