It means that they did not draw everything exactly the right size. If a map is drawn to scale, you can take a ruler out, measure things, and figure out how far away they are. If it's not drawn to scale, then it's just a picture showing how things are positioned relative to each other.The same thing is true in math. If it's drawn to scale, you can figure things out with a ruler and compass. If it's not drawn to scale, you have to use mathematical principles to calculate everything, based on whatever measurements might have been given.
