MAhr - Milliamps for 1 hour so 1000mAhr = 10 hrs pulling 100mA of current or 1hr at 1000mA (1000 mA = 1 A of course) So it shows how much power/electricity the battery holds / will last So more mAhr, and the long it lasts by that increased ammount.
Milliampere hours. If you know how many milliamperes your load uses, you can calculate how long the battery will last on a charge. With cell phones the load is constantly changing depending how much they use the display, make calls, GPS, etc.