Per TSN's Chris Johnston, the Oilers will not be retaining any of Puljujarvi's salary, which means that the Hurricanes will take on his full $3M cap hit. This is interesting because what it essentially means is that the Oilers are clearing space for another trade ahead of Friday's deadline.
As far as what the Canes are getting in Puljujarvi, they're getting a defensively responsible forward who can play a little more of the physical side, but who struggles to finish. You don't have to look to hard to find evidence of his issues with finishing, as Puljujarvi has scored just 5 goals and 14 points in 58 games this season with the high-octane offense Oilers.
The Oilers are believed to be in on several defensemen, including Jakob Chychrun, Vladislav Gavrikov and Mattias Ekholm. Having opened up $3M in cap space will go a long way in helping them to acquire a difference-maker on the blueline - especially if they can work in some salary retention.