Software testing metrics are important for many reasons. Most importantly, they are decision points that lead you to take action. The metrics you choose determine how effective those actions are in improving your quality level.
Software testing metrics also help you judge how efficient your testing efforts are and how productive your test team is. How many test cases are added for new release? How many tests pass in the first run, how many failed and require a retest? Which bug reports were filed in each cycle?
TestRail helps you keep track of those testing metrics and much more. Reports on various levels give you insights about individual test runs, milestones, and project status with high level project reports. All project activities and test results are archived so that you can learn from the past, identify trends, and be better prepared with each new release cycle.