The purpose of the Plug’n Pals app is to help owners of electric cars communicate with others as they share plugs and parking spaces.
When you see a site with a Plug’n Pals sign, you can scan the QR code with an app like Scan and Plug’n Pals will add that site to your list of favorites. You can then read and post messages for that site. This is how you can find out when the other person expects to be done, whether they mind you taking the plug before they return, etc.