Cardio Bursts target the cardiovascular system and raise the heart rate. Choose an exercise mode with which you are already familiar (walking, biking, running, swimming, calisthenics) and then perform quick cardio energy bursts at a vigorous intensity level, followed by a recovery period at a normal exertion level (low to moderate intensity).
The common format is a 1:2 ratio of high to moderate intensity (for example, 20:40 seconds or 1:2 minutes high:moderate intensity). The overall duration for the cardio burst session can run anywhere from 5-30 minutes maximum).
For clarification on how to monitor your exercise intensity level - based on RPE, Heart Rate, Talk Test, Steps per Minute, or a combination thereof - please refer to the flier put out by the ACSM. Because this type of activity can be a stress to your body and cardiovascular system, only attempt this exercise format if cleared by your physician.
https://nutritiouslife.com/sweat-often/short-cardio-workouts/
https://www.cnet.com/health/fitness/is-hiit-bad-for-you-the-downsides-of-high-intensity-workouts/
https://www.circlehealthgroup.co.uk/health-matters/womens-health/10-benefits-of-hiit
https://www.honorhealth.com/healthy-living/how-hiit-your-exercise-targets