The drone LED indicators are located under each motor and at the rear of the aircraft. The LED indicates the current state of the aircraft. See diagrams below for indications.
INITIALIZING / WAITING FOR RC SIGNAL
(Front: Red, Rear : Red / Green / Yellow alternating fast blinking LED)
READY TO FLY (ALTITUDE / POSITION / SPORT MODE)
LANDING MODE (Front: Red, Rear: Yellow / Blue)
Drone LED also helps to orientate yourself while flying.
Also you can find some other auxiliary LED for Drones that can be found on this guide