If you are asking what the saying means then here is answer one:
1. Many conservatives or people who hold traditional values often refer to America as the “city upon a hill” since it interprets as superiority, almost to say that America is set above other nations.
If you are asking about “The City Upon A Hill” By John Winthrop then answer two is correct for you:
2. “The City Upon A Hill” is a sermon [oration, lecture on biblical topics] called “A Model of Christian Charity”, which states that they (Puritans) intended to live so well, so righteously, that everyone would see that there was a right way to live. People would want to be like them. They would adopt their version of religion.