The instruments were mainly included in HeliSimRC so that you could see stick positions when playing back a recording.
The two center dials indicate the stick positions, both during normal flight, and playback. The idea being that an experienced pilot can record a maneuver you're trying to learn. Then you can play it back, and watch the stick positions necessary to perform the maneuver.
In addition to stick positions, HeliSimRC provides some other indicators.
Rotor RPM
Main rotor RPM is indicated by the dial at the far left. Zero is at 7 oclock on the dial, with 1000 RPM increments.
Speed
Air speed is at the far right of the screen. The speed indicated is the speed of the model in any direction.
Wind speed is not included, so this is actually model speed over the ground.
Zero is at 7 oclock on the dial, with 10 MPH increments.
Altitude
Altitude is the second indicator from the right. This is the models height over the ground in feet.
Zero is at 12 oclock on the dial, with 10 increments.