Why is the chemical symbol for sodium Na instead of S?

The chemical symbol for sodium is Na because it is derived from its Latin name, natrium.12

The symbol S is already assigned to sulfur, which is a distinct nonmetallic chemical element. In the early 19th century, the Swedish scientist J.J. Berzelius proposed that chemical symbols be based on the Latin names of elements to create a standardized system for chemistry. Because many common elements had names starting with the same letter, using Latin roots helped ensure each element received a unique and identifiable abbreviation.32