A KPI is a realtime indicator of a particular metric. For example, consider your car dashboard. When you look at it, the information that you're looking for is your current speed, fuel tank status, among others.
Notice that you're always interested in the current value of the metric like the speed. You use this information to make a decision which results in an action like slowing down or speeding up. You're always looking for the current value, and knowing the speed you were going 5 minutes ago doesn't help you now.
The KPI Component is similar to that in your RazorFlow Dashboard. It provides the stakeholders of the dashboard the current information used to make a decision.