To access the debugging tools, you need to click the sixth icon on the left-hand side panel icon bar, which usually shows a Show the Debug Navigator tool tip, and this will give you direct access to the debugging tools.

Understand that accessing this panel without running a game on the device will show you a totally empty panel. You must have a running game on the device to start seeing the tools shown here:

The first part called UE4Game has general information about the game. It is not much, but it is useful anyway. It gives you the PID value, which is the process ID of 601, and the current state of this process, which is obviously Running.

The second row of the toolset is the CPU. Accessing it will show you how many threads the device is running at the moment, the performance of each thread, and the utilization of each running process. Because you are running UE4Game, it will be the main focus here; any other running processes on the device will be listed in Other Processes. The amount of free CPU capacity will be listed in Free percentage.

The third row is Memory and it looks a lot like the CPU tool; in fact, it works in the same way, and the only difference is that the memory tool measures the memory capacity in MB.

The last row is meant for the FPS measurement. FPS is short for frames per second. A good game should be running on 60, but since complex games usually can't reach this frame rate, 30 is a good frame rate. The highest frame rate is the best and the lowest frame time is the best as well, because a low frame time would mean a high frame rate. As you can see, the frame rate is 60 and the frame time is 6.0ms, which means rendering the frame took 6 milliseconds from the device. This is very fast. Usually, its value would be something near 15 to 20 milliseconds for more complex games.