what does a map scale show
A map scale shows the distance on a map compared with the actual distance.
For instance, a map scale may indicate that 1 inch on the map represents 1,000 miles in the real world.
Check this site for more information.
http://geography.about.com/cs/maps/a/mapscale.htm
Distance
A map scale shows the relationship between the distances on a map and the actual distances on the Earth's surface. It helps you understand the proportion of the map's features to their real-world sizes.
A map scale can be represented in three different ways:
1. Graphic Scale: It is a line or bar that is divided into segments representing specific units of distance, such as meters or miles. By comparing the length of the line on the map to the corresponding distance on the ground, you can determine the actual distances between locations.
2. Verbal Scale: It is a statement or written description that expresses the map scale in words, such as "1 inch equals 1 mile" or "1 centimeter represents 100 kilometers." This type of scale is helpful when there is limited space on the map to display a graphic scale.
3. Representative Fraction (RF) Scale: It is a ratio or fraction that shows the relationship between a unit of measurement on the map and the corresponding distance on the Earth's surface. For example, an RF scale of 1:100,000 means that one unit of measurement on the map represents 100,000 of the same units on the Earth.
By referring to the map scale, you can determine the distance between two points on the map with respect to their actual distance on the ground.