Cardiovascular exercise is exercise where you work out at an intensity that significantly increases your heart rate and breathing tempo.
In order to burn the most fat during cardio training there is a target heart rate that you should exercise at. You should exercise at 65%-75% of your maximum heart rate. Your maximum heart rate is 220 minus your age. If you can do intervals during your training, in other words take your heart rate even higher for a few minutes and then bring it down to a lower level again, you can increase your chances of losing weight faster.
Examples of cardio training are: