Well the flow coefficient is usually given as the Cv and is an indicator of the flowrate that will occur at a given pressure drop, dependent upon fluid, etc. The full details are given in ISA S75.01
The valve opening will tell you how far the valve has stroked to reach a certain Cv.
It can reflect flow characteristic information associated with rangeability. The full open Cv defines the capacity. The characteristic of the curve reflects the ability to throttle. If the Cv increases quickly (quick opening) then the throttling ability is not as good as if the Cv to position is more linear or begins increasing more quickly toward the end of travel (such as equal percentage).
