What is the argument of a function?

In mathematics and programming, an argument of a function is the input value you pass to it. For example, in f(x) = x + 2, the value you substitute for x is the argument.

For deeper study, you can read this article on TutorialsPoint - Function Arguments.

In computer science terms: when you call a function like print("Hello"), the "Hello" part is the argument. Functions can have single, multiple, or even optional arguments.