Honesty-humility is the sixth factor in the HEXACO model of personality: the tendency to be sincere, fair, uninterested in wealth and status, and modest, rather than manipulative, rule-bending, greedy and entitled. The Big Five has no factor for it, and folds most of what it measures into agreeableness.
Where it comes from
Ashton and Lee (2007) argue from lexical studies, in which every trait word in a language is collected and the ratings people give on them are factor analysed, that the words keep sorting into six groups rather than five once languages beyond English are included. The sixth group has four parts: sincerity, fairness, greed avoidance and modesty. The other five correspond roughly to the Big Five, though HEXACO moves anger into low agreeableness and sentimentality into its emotionality factor. Their case for the extra factor is that it predicts what the Big Five predicts poorly: taking advantage of other people, delinquency at work, and materialism.
How it relates to the Big Five
Ashton and Lee (2005) compared honesty-humility with Big Five and Five-Factor Model measures and found it only partly covered. It correlated moderately with agreeableness, and most closely with the facets that ask about straightforwardness and modesty, but much of what it measures was not captured by any Big Five scale. On the 120-item test here, the nearest relatives are the morality and modesty facets of agreeableness, which ask about telling the truth, using other people and thinking oneself better than others. Read together they give a rough position on the factor, not a score on it.
What the factor does not mean
A high honesty-humility score is not moral superiority; it is what a person says about their own sincerity, fairness and appetite for status, with the limits of any self-report. A low score does not mean a person has lied or cheated in any particular case; it describes a willingness to bend rules and use charm for gain across situations. It is not the same as agreeableness: a charming manipulator and a sincere pushover can score alike on agreeableness and far apart on honesty-humility.
What it means for your results
This site measures the Big Five and does not yet have a HEXACO test, so there is no honesty-humility percentile here. The Big Five test gives you the morality and modesty facets of agreeableness, which are the closest Big Five reading of the factor, and the comparison article sets the two models side by side. If your question is about sincerity, fairness or greed, those two facets are the ones to read.
The Big Five test takes about twelve minutes and scores all six facets of agreeableness, with percentiles against 410,376 people.