These LEDs contain three separate LED chips, red, green and blue. By driving the three chips separately, you can produce any colour that you wish, including white light.
They are packaged in the standard 5mm milky white diffused LED package but have 4 leads, not 2, with a 1.25mm pin spacing (there is one common cathode lead and three separate anode leads - one for each colour).
Specs are: Red: 800mcd; Green: 1200mcd; Blue: 400mcd, all at a fairly wide viewing angle of around 50 degrees. Continuous current per LED chip is 20mA (60mA for total package).