I'm going to guess a bit here.

Turn the dial until the shutter speed you are using is adjacent to the film speed (EI) you are using.

As the needle moves in response to light, it will point to a number adjacent to an f/stop.

The f/stop is the one you need to set on your camera (assuming the meter is accurate).

If the dial rotates appropriately, you may be able to start off instead by setting the f/stop you intend to use adjacent to the film EI, and read the shutter speed closest to the needle.

Actually quite an elegant approach.