On icing instead of racing to the puck and icing being called based on who touches the puck first, it is based off who gets to the hash marks first. I am referring to the marks on either side of the face off circles close to the nets if that makes sense. It is supposed to cut down on injuries that happen when guys go full speed crashing into the boards to get icing (or no icing) called in their favor. It's kind of hard to describe.
They use it in NCAA hockey and some other leagues around the world, so you may be able to find a video of it that makes it clearer than the rambling mess I just typed out.
That explains it pretty well. To help illustrate it a little more: There is essentially an imaginary line, that is parallel to the end line, between the two defensive zone face off dots (same level as the hash marks on either side of the circle).
Then, on any potential icing, the linesman (not the referee), will whistle the play down if the defensive has reached that point prior to any offensive player, but if an offensive player is getting to that point first, and it appears they would win the race to the puck, then they don't blow the whistle, and the racce is still on to see who will touch it first after it crosses the end line.
Confused yet? Like anything, the potential rule has pros and cons, and those who want it, and those who don't.
The part that does not make sense to me, is if the offensive player gets there first (to the imaginary line at the level of the face off dots), then the race is still on, and the scenario is just as dangerous as the current icing rule.
But, in any case, the players will vote on it at the end of the pre-season, and then it will go to the NHLPA for a vote, and if it's found in favor of, it will be a new rule for this season. From what I've read online, a lot of players and coaches don't like the Hybrid Icing rule, so there's a good chance it won't pass.