A more thorough explanation:

Definition: A supercargo is a person who is hired by a cargo owner to sell the cargo that has been shipped and to buy returning cargo at the best possible prices. They are also known as commercial or foreign agents of a merchant.

Example: A company that exports goods to foreign countries may hire a supercargo to take charge of the cargo and sell it to the best advantage. The supercargo will also purchase proper commodities to relade the ships on their return home.

Explanation: The example illustrates how a supercargo is responsible for selling the cargo and making purchases under the general instructions of the cargo owner. They are hired to ensure that the cargo is sold at the best possible price and to purchase goods that will be profitable for the cargo owner. The supercargo is the agent of the owner and is responsible for disposing of the cargo and making purchases on their behalf.