A jeter stat is a statistic that is mostly irrelevant and made up to make someone look good. This was done frequently to make it look like Derek Jeter didn't suck at baseball.
Yankee Fan: Derek Jeter is the has hit the most doubles of any shortstop in New York in games played from mid May to early June when the temperature is between 55 and 60 degrees and there is a full moon obstructed by clouds.
Literally anyone else: Yeah, but nobody cares. That's a total jeter stat.