This is a combination of the PERCENTAGE of PRICE OSCILLATOR (PPO) and Momentum.
When both oscillators are up in the same direction it is buying (green bottom and green oscillators), when both oscillators are down it is sell (red bottom and red oscillators. When they do not agree (silver bottom) it is to keep doing nothing.
You can also see the change in trend with the candles as well. same colors as the background and the oscillators.