What does the support factor indicate?

The support factor indicates the percentage of your own power that the drive unit gives you.
In Turbo mode, this is up to 340 percent, which means that if you pedal with 100 watts, you get 340 watts from the drive unit for a short time. In Eco mode you get 60 percent support, which means that when you again pedal with 100 watts, you get 60 watts from the motor.