Leds
The board has two leds, a green led named LED0 and a red led named LED1, which provide info about the controller's current condition. There is also a third led, which is related to the HC06 bluetooth module.
Red Led (LED1)
The red led is so to say a heartbeat, it should blink at a frequency of about 1.7 Hz in normal operation. In case of an error condition, such as low battery voltage or missing IMU, it blinks however much faster.
Green Led (LED0)
The green led in principle tells about the current state of the controller, e.g. at startup it undergoes a sequence of ever faster blink sequences. When the normal state is reached the green led is permanently on (it is not really permanently on, it just seems so, the green led is in fact used as a debug output for the development of the firmware).
Yellow Led
This led is directly connected with the HC06 bluetooth module. Hence, it doesn't tell anything about the working of the STorM32 board, its meaning has to be read off from the documentation for the HC06 module.
The permanent blinking of this led is actually a bit anyoing, and one may wish to deactivate it (since v1.3, scratch through the solder jumper on the bottom, or desolder the respective resistor).