It's too early to explain this one.
Mil's are like degrees (on a compass). Except there are 6400 mil's in a circle instead of 360. There are roughly 17.777 mil's in one degree.A mil is roughly worth 1 meter inwidth or heightat 1000 meters. Confused yet? I was when my drill sergeants first tried to cram this down my throat years ago.

We use mils for lots of reason, but for your scope it's used for range and deflection estimation. To estimate range with the mil dots, you need at least one known factor. Usually theheight of your target or something next to it. The easiest thing to use is an adult male torso, which is roughly 1 Meter tall. Or ahousehold doorway which is roughly 2 meters tall.If you look at a 1 meter tall target through your scope, and it covers 1 mil, guess how far away it is? 1000 meters. If it covers 2 mil's, it's 500 meters away. get it? It may be confusing nowbut when it "clicks" you'll slap your head and say, "this is so easy"!