You need to put special soles in your ski boots and that monitors your skiing and gives you a rating, called your Ski:IQ. Based on this, you can then do 'lessons' for different areas of improvement- you will need headphones for this aspect as it will give you instant feedback. It's been a few years since I used it but if I recall correctly, I was trying to improve my turns. Carv would then signal each turn whether I was getting enough edge to be effective, via the headphones, with a noise.
From the feedback I have read, it's more beneficial for high intermediate to advanced skiers as your posture, position should be all correct and it's monitoring your foot pressure which is something a ski instructor can't see but would only be able to guess at.