noun
A person who sells goods or services, often in a commercial or agency context.
彼は中古車の販売人として働いている。
He works as a used car seller.
販売人は商品
The sales agent explained the product features in detail.
売り手 is a general term for a seller, often used in contrast to 買い手 (buyer), and does not necessarily imply an agent role.
Compound of 販売 (selling) + 人 (person). The exact historical derivation is uncertain, but the word follows a common pattern for occupational nouns.