There are 3 different colored LED in it, RED, Green and Blue. You can get the colors of rainbow by turning on these Leds separately or at the same time. 🙂
Long tip is the plus, after giving the voltage to plus tip, the color of the leg which you connect to the ground will be lighted. It operates on voltages between 1.5-3V. It has to be used with necessary resistors for 5V and above voltage values.