This is the 10th most frequent French word.
sur
"Sur" in French means "on" or "upon."
Here, 'sur' is used to indicate a physical position or location: 'on'.
Le livre est sur la table.
The book is on the table.
In this sentence, 'sur' conveys dependence or reliance: 'on' as in 'based on' or 'relying on'.
Il s'appuie sur son expérience pour résoudre ce problème.
He relies on his experience to solve this problem.
Here, 'sur' is used in a numerical or proportional context: 'out of' or 'among'.