A more thorough explanation:

An envoy is a high-ranking diplomat who is sent to a foreign country to carry out a special mission or to serve as a permanent diplomatic representative. They are also known as a messenger or representative.

For example, if the President of the United States wants to negotiate a trade deal with China, he may send an envoy to China to discuss the terms of the agreement. The envoy would be a highly respected diplomat who has the authority to negotiate on behalf of the President.

In international law, an envoy is a person who heads a legation rather than an embassy. However, in current usage, the term is honorific and has no special significance.

Overall, an envoy is an important figure in international diplomacy who represents their country and carries out important missions on behalf of their government.