Leaning gently forward on the pedals allows the rider to go forward, and leaning gently back toward the center will stop the wheel. The wheels can go backwards, so if you lean gently backward the wheel will move back, as well.
The safe limit for riding is 14km (approximately 8.5 miles) per hour. If the wheel reaches that speed, the pedals will automatically tilt up to remind the rider of the approaching speed limit. Slow down immediately and do not continue to accelerate as the pedal may be raised to an unsafe angle for riding.