Understanding Percentiles
The best way to understand percentiles is to imagine yourself in a room with 100 other people. If everyone in that room was assessed regarding a particular fitness test at the same time, then your assessment percentile would represent your standing in that group.
For example, if your percentile was given as 70%, then 30 people, or 30% of people in the room would be able to perform better than you or worse than you, depending on the criteria of the particular test.