Instructions: This shows the output from the GPS module, which should be plugged in the GPS port on the ArduPilot board or shield. Typically, it will only be meaningful if you're outdoors, with a clear view of the sky. Some GPS modules will get sat lock indoors if you're in a wooden house without too many floors between you and the sky, but it's very unpredictable. Typically GPS modules require as much as 15 minutes to get sat lock if they're "cold starting", which is to say they haven't been powered on for a day or more.
Troubleshooting: If you're outside and have given the module time (at least 15 minutes) to get sat lock, causes for no data can include: