The props work in a similar way a transmission in a car works. Props have two numbers: The diameter and the pitch. 10-7 = 10" diameter 7"pitch. The diameter is pretty much explanatory. The pitch works this way: This is the amount of air that would move through the prop arc in one revolution. One inch moves 7 inches of air, or the prop would, in theory, move 7 inches through the air in one revolution.

So, take the revolution of the engine, say for easy definition, rotates at 10,000 RPM at full throttle (maybe, maybe not, but for explanation purposes, say 10,000RPM).

So, that means that in one minute, the prop will move 70,000 inches or 4200000 inches per hour or 350000 feet per hour orjust over 66 miles per hour. That is in theory.
Also, think of the prop acting as a transmission on a car. If you want to climb a steep hill, you downshift to a lower gear and the engine goes higher in RPM at the same speed, but you have more pulling power. Back off to 10,000 RPM and you have a slower traveling plane but with more pulling power and faster acceleration. Increase the pitch, you have a faster plane at the same RPMbut with less power to get you there so it tkes longer to do the same work.

Hope that helps a bit.