It means there is not enough room for the laser to accelerate and decelerate beyond the engraving or cutting areas. As the laser is cutting or engraving your project it needs a little extra space to slow down, change direction, and speed back up. This error says there is not enough space.
You can try moving your project closer to the center of the bed or slowing down the speed.
You may also see this error if your file is too big or there is not enough space available on the controller.