If you are a vendor, it means you’re a person selling something, whether it’s hot dogs from a food cart or computer software for a tech company.
The word vendor comes from the Latin word vendere, meaning “to sell.”
Vendor is a name for people who sell things on the street, such as a hot dog vendor, but it can describe those who sell any kind of goods or services, especially a specialized product.
A store at the mall isn't usually called a vendor, but you could use the word to describe the person or group that supplies the store with special products or services.