You have to lines on a 1602 display: line 0 and line 1. And 16 columns: 0 to 15.
The fact that there are three lines should have set off alarm bells. NEVER blindly trust code you get "on the Internet" (libraries tend to be quite OK, especially if referenced to from different sources), always check it carefully and make sure you understand every single line. Look up commands that you don't know.