Numerical Trackers (Value Indicators) are used to track numerical progress for individual contacts.
They must have a unit e.g. £, $, etc, or you can set them to “no units” if a unit is unnecessary
Examples
Example user cases are when you need to track:
Salary
Temperature
Distance Run
These are all numbers that are likely to change over time. This is why they should be tracked in stories as every story is time-stamped which enables you to see trends in progress over time.