Notice we specified the source of the database we wanted to copy as well as the destination. In this case, they are the same server. You must specify it this way so that it is clear we are operating on the same server.
Notice how we specified the new name. We used the <old_name>:<new_name> syntax. You can do this for as many databases as you want to copy. That's right - you can copy multiple databases with a single command renaming each along the way.
To copy a database without renaming it (if the destination is a different server), you can omit the :<new_name> portion.