This is a great drill for dialing in the counterbalancing (angulation) and the upper body, but also good for balance, not to mention keeping the hands still in place - which is usually a struggle in itself.
The idea is to keep the poles in front of you, parallel with the snow and do not let them bank or rotate in any way, while holding them with the arms in front and open wide.
This in turn should reflect in your body staying upright on snow (angulating through the turn) and coiling through the turn as well.
Also, complete your turns more and more, to make the skis point as much to the side of the hill as possible, to improve coiling: you must feel quite some strain from Coiling in the core and lower back, as you separate the upper body and counter it to keep it facing down the hill (keep the poles from rotating).
Get into the usual stance. Flex knees slightly. Put the poles together and keep them out in front of you, horizontal - see photo. Do one run while focusing on holding the poles in the exact same place, while turning.
Don't let the poles tilt either way and don't let the poles rotate. Keep exaggerating and increasing the range of movement to increase the skis angles and complete the turns, to strain the back and feel the extremes of these movements. Every run do MORE and MORE!
The result should be that the shoulders and hips stay more level with the snow and facing down the hill, rather than following the skis: no tilting and no rotation.
Here's an idea on how it could look like:
A way to progress is to increase the effective length of the banking "indicator" by sliding the poles relative to each-other as in the photo below:
This is a good drill for green, to dial in the basic movements and send the message of keeping a still upper body as well as improving the balance. It becomes a critical drill at blue and black, where the increased range of movement makes it harder to maintain a calm upper body.