Once you've opened the interface, you may find it rather hard to tell what each tab is for, but once you focus it's quite easy to understand what each refers to.
The first tab gathers all of the general information related to your GPS. This feature lets you see your GPS's signal-to-noise ratio (SNR).
The second tab shows you the position of satellites on the compass, as well as the intensity of their signal, so that you always know where they are. This feature will help you improve your connection when you find yourself in an unknown location or somewhere with very little coverage.
In the next tab, you'll find your exact position on the map using the current coordinates of your location, as well as a sun icon that shows what part of the world is receiving sunlight at any given time.
The fourth option shows your altitude, speed, and direction of movement—a very useful tool when you're traveling by car, since it displays your movement on the map.
Finally, GPS Test provides info on the date, weather, and local time at your location, as well as the time of sunrise and sunset.