How many miles will I be able to go on a single charge?

Without getting too technical, depending on your ebike's battery, mileage can range from 20 miles to 90 miles per charge. There are many variables that affect your range. They include obvious things like your weight, your ebike's weight, the terrain (hills require more battery), and how much you are contributing with your pedaling. Range is also affected by tire pressure, the type of road (or trail) surface you are on, and - if you are pedaling - selecting the gear(s) which will help you contribute your pedaling power effectively.