The default settings are:
Long-term EMA: 200 Period.
Short-term 1: 50 Period.
Short-term 2: 20 Period.
So according to the default settings, when the 20EMA is above the 50EMA, and the 50EMA is above the 200EMA, the area between the 20EMA and the 50EMA will turn green. When the 20EMA is below the 50EMA, and the 50EMA is below the 200EMA, the area will turn red. When the EMAs are all over the place (ie. price is consolidating), the area will be painted white.
You can change the colors in the indicator settings menu. To remove the white background, change the transparency to 100%. Unfortunately pinescript does not allow you to do this using code, otherwise I would have made that a default feature.
Enjoy! Let me know if you have any questions.