This phrase may be related to the American saying "Get a life!" This is said to have been first uttered by William Shatner on the television show Saturday Night Live, in a comedy sketch where he played himself interacting with a group of Star Trek fanss. The implication in the sketch was that none of the fans had a real life, and that they needed to move out of their parent's basement, get a job, a girlfriend, and buy a house with a mortgage.
However, many people who are actively involved in those activities admit that they feel some or all of the time that they would be happier without a real life.
RL is an abbreviation for "real life," with the meaning "not on the Internet." For example, one can speak of meeting in RL someone whom one has met in chat or on a message board, or of not being able to use the Internet for a time due to RL problems.
It is often abbreviated to IRL (In Real Life).
It has been objected that the Internet is real life; after all, the people on the other end of the connection are real people with real lives. Some prefer the expression f2f (face to face) for that reason.
See also: quality time