What does the “Target” column mean on the entrants page?

The target column is simply the average winning time of an event over the past 4 years divided by your “Runner rank”. Like “Runner rank”, it is meant to be a fun way to view your future performances. If you are not happy with the target the computer gave you, use that as a motivator to prove it wrong. It is not perfect and is not meant to interfere with your actual running.