Hits measures the total number of hits a batter has over the season including singles, doubles, triples and home runs. Hits doesn't include situations where the batter reaches the bases due to an error or a fielders choice.
More about Hits Leaders
Players topping the hits leaders charts are often, though not always, the same as the players topping the batting average charts. Cleanup hitters will often have high batting averages, though due to their batting third or fourth in the lineup over the course of the season they won’t get quite as many plate appearances to rack up hits as players at the top of the lineup. As a result, players at the top of this list almost always 1) need to bat at the top of the lineup, and 2) need to stay healthy throughout the season in order to accumulate as many plate appearances as possible. Having a hitter-friendly home ballpark also does not hurt in accumulating as many hits as possible, as well as having a tendency to walk a little less than the average player, thus putting the ball in play more frequently.