The STorM32 board has two LEDs, a green LED named LED0 and a red LED named LED1, which provide info about the controller's current condition. On the v1.x boards there is also a third yellow LED, which however is related to the HC06 Bluetooth module.
Red Led (LED1)
The red LED1 is so to say a heartbeat, it should blink at a frequency of about 1 Hz in normal operation. In case of an error condition, such as a low battery voltage or missing IMU, it blinks however much faster in order to signal the error condition.
Green Led (LED0)
The green LED0 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. For more details see Getting Started: First Startup.
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 (see here).
The permanent blinking of this LED may be annoying, and one might wish to deactivate it. On the v1.3x boards on can scratch through the solder jumper on the bottom, on the v1.1 and v1.2 boards desolder the respective resistor.