There are several different varieties of multicolor LEDs. One is just two or more LEDs in a single package. The color depends on which of them you turn on, how brightly and/or (if you're sending pulses to them rather than just on/off) how often and how long. Given that yours appears to have four wires coming out of it, I'd suspect that's what you've got. (I don't recognize the particular unit, but if you can find a part number on it you can probably look it up in a manufacturer's catalog or on the web.) Another is two LED's wired "back to back". Since LEDs are diodes, in this configuration you get one color when voltage is applied in one direction and the other color when you reverse the voltage. That's mostly used for the simple red/green/off case, but again if you want to play with pulsing voltages you could get intermediate colors. And there are probably some which incorporate the LEDs and control logic in a single package. But you'd need to check the specs for that particular part to find out how those expected to be wired and used. If you bought this unit, whoever you bought it from can probably point you to documentation. If you're recycling it, you're going to have to do a bit of research.