Answer:
it really means the binding of the skiing and the adjustment of it.
That makes no sense.
The DIN of a ski is very important to skiers because it is how easily the ski will release in a fall. The lower the number the easier the ski releases. Generally the lowest is around three and highest, pro racers, can be above 24. If the DIN is too low the ski can release when it is not supposed to, often if you hit a bump when going fast. An annoying crash at best, potential broken bones, or worse, at worst. If it is too high the skis will not release when they should. At best nothing happens, but this is very rare. Often you twist things, mostly knees but if you are unfortunate you can smash your skis into your face which really hurts or break bones by twisting your legs in ways they shouldn't.