A more thorough explanation:

Definition: A diplomatic representative, ranking below an ambassador, who possesses full power and authority as a governmental representative, especially as an envoy of a sovereign ruler. This officer is often regarded as the personal representative of a head of state.

Examples:

• A minister plenipotentiary may be sent to negotiate a treaty or agreement with another country on behalf of their own government.
• They may also be responsible for representing their country's interests in international organizations or conferences.

These examples illustrate how a minister plenipotentiary is a high-ranking diplomatic representative who has the authority to act on behalf of their government in important international matters. They are often seen as a direct representative of their country's leader and are responsible for negotiating and representing their country's interests in a variety of settings.