In 2009, Buick LaCrosse had a button and two trees. What do you mean?

Indicator light of in-vehicle air quality monitoring system. This system can monitor the air quality inside the car, and automatically adjust the ratio of circulating air inside the car to fresh air outside the car according to the monitoring results to keep the air inside the car fresh and healthy. When the system is turned on, the indicator light will light up, indicating that the system is working.