Question: what is a scale 1 to 10?
Answer: The scale is shown as the length in the drawing, then a colon (":"), then the matching length on the real thing. Example: this drawing has a scale of "1:10", so anything drawn with the size of "1" would have a size of "10" in the real world, so a measurement of 150mm on the drawing would be 1500mm on the real horse.