Jerusalem is a big city with lots of different names that people use to talk about it. Some people call it "Yerushalayim," which is the Hebrew name for the city. Other people call it "Al-Quds," which is the Arabic name for the city.
Jerusalem is also called the "City of David" because King David founded the city a long, long time ago in history. It's called the "Holy City" because it's a very important place for many religions, including Judaism, Islam, and Christianity.
Some people might also call Jerusalem the "Old City" because it has really old buildings and walls that have been there for thousands of years.
All of these different names can be a little confusing, but they all refer to the same beautiful and historic city.