[{quoted}](name=Riot Reinboom,realm=NA,application-id=3ErqAdtq,discussion-id=MxjyfJB6,comment-id=001c0000000000000005,timestamp=2016-03-05T22:27:00.591+0000)
It carries your current XP at that level forward, but not total XP. In order to level, you'll still need to play a game but excess will carry over.
This is most significant nearing level 30.
As an example (none of these numbers are exact but they will communicate what the implementation):
Let's say you have 2500 XP and you require 3000 to get from level 27 to 28 in the current system.
In the new system, that might be changed to, say, 1500 to get to 28. When the change happens, you will now be at 2500/1500 experience but still level 27.
Playing a game will level you and carry your experience. So you will be at 1000 experience into your next level (on your way from 28 to 29 now), plus the experience you got for the game (so, probably closer to about 1130 experience).
Each level still requires a game to get, but it's possible that you could be sitting at level 28 now and it suddenly only requires 2 games (win or lose) to be level 30.
^this example will fit me exactly and hopefully will be a significant change since I'm level 27. Never been so happy for the next patch to occur