Hover the mouse pointer over the icon to view the total uploaded and downloaded internet data for the session. The icon appears in the system tray as 2 computer screens.
As soon as you install this internet usage monitor, it gets placed in the system tray. This will open up the Activity Monitor app. Alternatively, you can use spotlight search to open Activity Monitor, press Command + Space, type Activity Monitor and hit return. To open Activity Monitor, Open Finder Applications Utilities Activity Monitor.