It doesn't stand for 'Really Good Beats'
RGB technology allows us to light LED’s in almost any colour you can imagine. What this means is that your Novation RGB device will light up to match the colour of your clips in Ableton Live. Now you can see at a glance which clips are loaded, playing and recording.
The other advantage of RGB pads is that you can design, create and play colourful interactive light shows to enhance your performance.
The Gory Details
RGB stands for Red, Green and Blue. Red, Green and Blue are primary colours; by combining these, it's possible to create any colour in the visible spectrum.
You can create secondary colours yellow, cyan and magenta by combining two primary colours together:
Red + Green = Yellow
Green + Blue = Cyan
Red + Blue = Magenta
Combining all the primary colours together at equal intensity will give you white.
Red + Green + Blue = White
By combining different primary colours at different intensities, you can create shades of any colour in the visual spectrum.