In baseball, a lead or lead off is the short distance that a player stands away from their current base. The "leadoff hitter" is the first batter in the batting line-up for his team, or the first batter of an inning or a game.
On the bases
In baseball, to lead off, or to take a lead, refers to the position a baserunner takes just prior to a pitch, a short distance away from the base the player occupies. A "lead" can also refer to that distance. A typical lead is six to ten feet (two to three meters) from the base. If the lead is too large, the runner risks being picked off. If the lead is too small, the runner has a disadvantage in reaching the next base, whether in a stolen base attempt or in connection with the next batted ball.
The first batter
Also in baseball, the "leadoff hitter" is the first batter in the batting line-up for his team. The leadoff hitter is usually a player who has a high on-base percentage and the ability to get himself into scoring position by stealing bases. Leadoff can also refer to the first batter of an inning or a game.