What are four typed lines of prose?

Hey guys. I'm writing my first paper using MLA formating. I'm on that purdue owl website that tells you how to write a paper using MLA formatting. I'm up to the part where it tells you how to cite quotes. It says that to indicate short quotations (fewer than four typed lines of prose or three lines of verse) in your text, enclose the quotation within double quotation marks. What does fewer than four typed lines of prose or three lines of verse mean? Please help the paper is due soon and I didn't even start writing it yet. I'm trying to figure out this whole MLA in-text citations thing. Could anyone please answer my question? And please give any examples and any links to any site or anything that will help me. THANKS SO MUCH!!