What does the indicator light second gear start means . and why does the car start off slow?

Second gear start was a feature on a few GM car models in the mid 90's. When engaged, the car will start off in second gear instead of first. This is why the car is slower while turned on. There is much less torque output starting out in second gear, providing improved traction while driving in icy and snowy conditions.

There is a button or switch somewhere that turns it on and off.