What I want to know is two points as below:
Is there anyone can give me an example or make an explanation?
A reverse line feed makes the cursor go back up to the previous line. A regular line feed makes the cursor go to the next line.
Edit: ThePower is correct, these terms originate from the days of line printers, "feed" meaning to feed the paper through the printer, in this case by one line, and reverse line feed moving the paper backwards by one line.