You can display infowindow message to each location using Wp Google map plugin. Follow below steps to Display infowindow message of each location:

Step 1 Go to Add or Edit Map page.
Step 2 Select ‘Display Infowindow’ radio button from ‘On Click’ tab. By default it is selected.
Step 3 Enter the Message in ‘Infowindow Message’ tab.

Infowindow Massage
Step 4Save the map and open it in a browser. You’ll see the infowindow message on the location.

Display Infowindow Message