An electrical energy meter is used to measure the energy used
in a commercial location or residential dwelling unit. It provides
a way for the energy provider to be able to charge people for
their energy usage. The device works sort of like the car mileage
odometer. One reading does not tell you much but the difference
between two readings measures the energy that flowed through the
device in kilowatt-hours.
In most parts of the country you will find either a digital meter or a dial meter. Both are very easy to read and your electricity provider puts both the previous meter reading and the number of kilowatt-hours you used on your monthly bill. Many energy providers even have web sites to help you to understand your meter and your bill.
When you find your meter (it may be outside where the electrical service line comes from the street or in the basement if you live in an apartment), besides the wheels, dials, or digital display with the numbers you will notice the edge of a small horizontal wheel. This will turn at different rates for different meters, but the faster it goes the more energy you are using.