As it currently stands, there is no direct interstate highway between Philly and New York. If you ever take a Bolt or Megabus between the two cities you'll notice it usually takes exit 4 on the Turnpike and drives through suburban Cherry Hill NJ to get into Philly. To get between the two cities you have to exit and take a more local road through NJ for a couple miles. This interchange will connect it so you can go directly from "Pennsylvania 95" to I276 to "NJ Turnpike 95". (Except now all called "95")
If you are driving direct from New York/Boston to DC, you'll in all likelihood never see this interchange and continue take the NJ Turnpike all the way down to Delaware in order to bypass Philadelphia traffic and construction.