They provide another means of informing you of battery state-of-charge, rather than having to count the bars. That simplifies it to a quick glance.
Bars Color StateOfCharge 1 purple 40-44% 2 purple 43-47,5% 3 blue 45-51,5% 4 blue 49-54,5% 5 blue 52-57,5% 6 blue 55-66,5% 7 green 64-77,5% 8 green 75-81% The threshold differs between charging and discharging. That means after driving electrically and losing a bar it's necessary more than just a braking to get the bar back and vice versa. The battery ECU of the car strives for around 60% SOC. SM-G950F ?