The result shows the maximum number of times your heart should beat.
If you know your Maximum Heart Rate, and as a bonus know your Resting Heart Rate, you can set some baseline training zones. The most accurate zones are done with a scientific metabolic assessment by New Leaf Fitness or other service. Another good way is to do a cardio assessment to help you define your zones. But there are many equations developed to help individuals to develop their personal heart rate training zones without that level of testing. They key is to experiment a little, and find the zone set right for you.
Measuring your heart rate can help you keep from making one of the most common mistakes that runners of all abilities make—running too fast too often, which puts you at risk for injury and burnout.