Sodium and chloride are the two elements that make up salt. This is expressed by writing NaCl, which is the scientific term used to express salt.
Table salt is perhaps the most common use of sodium. Sodium is an unstable element, and so is chloride. When mixed together, however, the atoms then become stable. Both sodium and chloride are poisonous to consume as standalone elements. The combination of the two makes the atoms safe for consumption. Chemically, chloride gives sodium an extra electron, and then table salt is formed.