In general, the higher the viscosity, the slower the flow of the liquid. The measurement involved determining the time it took for the liquid to run out the hole. Modern devices work on any one of several principals. Cambridge imparts a magnetic force on a piston and measures the speed. Another device uses a heavy piston and measures the speed, anothers rotates a cylinder inside a coaxial sleeve and measures the drag force on the sleeve.
Some devices vibrate and measure the attenuation which depends on viscosity and density.
Some devices force the liquid through a small hole at a controlled flow rate then measure the pressure across the hole to infer viscosity . If you are working with hydrocarbons like fuel or lubricating oil the conversion is simple. To get centistokes from centipoise, divide by the density. Of course to go the other way, multiply centistokes by the density to get centipoise. If you are using a Cambridge Viscometer software version 3C1.06 or higher the units can be set to display either Centipoise or Centistokes.