What Is Percentile?
A percentile shows where a value stands compared to the rest of a data set. If a score is in the 90th percentile, that means it beat about 90% of the other scores in the set. It's a way of ranking, not a percentage of correct answers.
Example
Scoring in the 95th percentile on a standardized test means you scored higher than about 95% of the other test-takers, whatever your raw score happened to be.