example.js

// Here's a function that takes three inputs, aka arguments.
function myFunction(x, y, z) {
  let a = x + y;
  return a * z;
}

// Calling the function means that those values are "bound" to the variable names we chose when defining the function.

// This function call:
myFunction(1, 2, 3);

// is equivalent to:
{
  // the inputs: myFunction(x, y, z)
  let x = 1;
  let y = 2;
  let z = 3;

  // after those variables are set, the actual body of the function executes:
  let a = x + y;
  return a * z;
}