What are variadic functions in accordance with C and C++?

Question

I am confused. As i asked the question previously about overloading in C, i got some answers.

Whenever i try to make others understand about this, I get confused in

Answer 1

As clearly said so, it used to accept any number of arguments.

Generally, there might be requirements for such method when the user doesn't know how many variables to be passed inside.

Eg: For requirement 1, you require to call the method with 2 parameters. For requirement 2, you require to call the same method with 3 parameters.