If you don't eat right, no amount of exercise will benefit you.
The problem is you're thinking that means
what you eat. What it really means, as the others have said, is
how much you eat vs. calories burned per day. If all you do is sit on the couch playing video games all day, you're going to have to eat a very small amount of food to lose any weight, because you're hardly burning any calories. If you're exercising like a madperson, you can (usually) eat a lot more and still not gain weight.
So what you need to do is
do some research on how many calories various foods that you personally like to eat contain, (vs. how many calories you think you may burn a day)and adjust portion sizes/meals accordingly. Salad's are great, but if you drown them in high-fat dressing and put lots of meat, cheese, and croutons in it, calories consumed can still be very high. There are some salads that have can just as many calories as a burger.

Also note, as I think someone already sorta mentioned, while you can theoretically lose weight eating nothing but small amounts of Cheetoes every day, that would not exactly be
healthy.You don't have to eat a super special diet of only certain foods to purely lose weight. Just eat lower calorie food items or smaller portions.
P.S. Not saying it's easy. It's not. Try Weight Watchers if you want/need a plan/structure to follow...as well as learn something.