Jordan's weight is in the 50th percentile. this means that he weighs 50 percent more than other children his age he weighs 50 percent less than other children his age the average weight for his age is 50 percent more than his weight 50 percent of children his age weigh less than he does

This means that: 50 percent of children his age weigh less than he does.
The term percentile is often used to describe the group of data that presented on quartile.

The first quartile = top 25% of the group
The second quartile = Top 50% of the group
The third quartile = Top 75% of the group
The fourth Quartile = Above that.