You can can configure the sort order of scores on a leaderboard from highest to lowest or lowest to highest.

If you wanted to rank players by number of points scored in a game you might use highest to lowest so that the players with the most points rank at the top of a leaderboard.

If you wanted a leaderboard to rank how long it took a player to do something you might use lowest to highest so that players with the fastest time (lowest value) rank at the top.