Answer:
Somewhere on the outside or in the basement of every building, there's a 'meter'
for every house and every apartment. It has a big glass shell over it, and inside
the shell you can see a spinning disk and a set of little clock faces with little hands
that point to little numbers.
The meter is keeping track of the electrical energy consumption (in kilowatt hours)
of one house or one apartment. The more electrical power is being used right now,
the faster the disk is spinning. The little clock faces are adding it all up ... If you
look at them today and again tomorrow, you'll see that one or two of the little
hands have moved to different numbers, because of the electric consumption
during that period of time.
From time to time ... usually once a month in most places ... an employee of the
electric company will physically walk up to your meter, read the numbers on it,
and take the information back to the office, where your bill will be prepared.