This is a 5mm common anode RGB LED. This LED basically consist of 1 red, 1 green & 1 blue LED in a single package. All these three LED’s share a common Anode and each of them have a separate cathode through which you can control the intensity of individual color.
Red, Green and Blue are the primary color and using these three colors you can generate any color that you want. Similarly you can make this LED glow in any color as per your requirement by controlling the current of individual LED’s or by using PWM technique.