Usually, the pronoun you refers to the person or group of people that the speaker is talking to. For example:
“You must complete this project by tomorrow!”
“You are the best students I’ve ever had.”
“What do you plan to do about this?”
Sometimes, “you” does not refer to any one person or any one group of people. Instead, it refers to anyone or everyone. In these cases, “you” has the same meaning as “people”:
“People have to work very hard to make a dollar these days.”
“You have to work very hard to make a dollar these days.”
“It is so smoggy in Los Angeles, that people can barely breathe.”
“It is so smoggy in Los Angeles, that you can barely breathe.”
“The only place people can get great pizza is in Chicago.”
“The only place you can get great pizza is in Chicago.”
The pronoun “they” has a similar usage, but is more often used to refer to a specific group of people:
“They say that it will be a cold winter this year.” (“They” refers generally to experts on the weather.)
“They are going to raise taxes again.” (“They” refers generally to politicians or to the government.)