Simplify the following text for a Grade 7 native English-speaking person.
Original: Two generations of fans of American League teams have grown up with the Designated Hitter rule being in place , and for many of them the designated hitter is as much a traditional part of baseball as the pitcher taking his turn at bat is for fans of National League teams .
Simplified: In baseball , a designated hitter ( DH ) is a person who bats in place of the pitcher in the American League of Major League Baseball . In the National League , the pitchers have to bat for themselves .