Scale is a measurement we use to give customers an idea of how big your model will be when comparing to the real-life object. If you see the scale 1:8, this means your completed model will be eight times smaller than the real thing; that is every dimension of the original is reduced by 8 times.
Remember this is done on a 3-dimensional scale and we are shrinking total volume.
You can find a lot more detail in our blog about scale, and how various scales affect accuracy of the final model.