Precision is the state of having little variation. It is often incorrectly used synonymously with accuracy. (Accuracy simply means centered on the target.)
Precision is often much harder to achieve than accuracy. That is because variation can be much trickier to adjust than moving an average.
Consider the temperature of an oven. If the thermostat is inaccurate but precise, it might read 400 degrees when it is really 380 degrees. It then becomes a simple matter to either replace the thermostat, or compensate for the inaccuracy (i.e. Kentucky windage).
But if the oven temperature fluctuates from 380 to 420 degrees, it is accurate (averages 400), but is very imprecise. That imprecision is much harder to correct. There are a large number of variables that could be contributing.
Precision stabilizes processes, helping provide quality outputs at predictable times.