“Really? They plowed my street the next morning.”

It snowed a couple of days ago. You're talking with one of the other mothers at your child's daycare about the snow. She says that there's still a lot of snow on her street. The snow has been gone since yesterday where you live, so you say:

 Really? They plowed my street the next morning.

they (did something)

In the example above, the speaker doesn't really know who got rid of the snow on her street, so she says that "they" did it. It's common to use "they" to talk about the people who are supposed to do something, when you don't really know whose responsibility it is. For example:

Looks like they finally got around to fixing that light.

Look at that (pointing to a sign) - they raised the price of gas again!

Did you know that they're making a new Ghostbusters sequel with the original cast?

plow the street

When it snows, the local government sends trucks out to push the snow off of the major roads. This is called "plowing" the road, and the tool on the front of the trucks that pushes the snow away is called a "plow".

The word "plow" also describes what farmers do to get their fields ready to plant crops in. In old times, farmers used to use a horse, donkey, or cow to pull the plow around their fields. These days, a lot of farmers use a tractor instead. But it's still called "plowing" the field.

The object of "plow" can be "the street", or it can be "the snow". When talking about farming, you can "plow the soil" or "plow the field".