what is the type of spread operator in javascript code example

Example: spread operator

function sum(x, y, z) {
  return x + y + z;
}

const numbers = [1, 2, 3];

console.log(sum(...numbers));
// expected output: 6
// This will add each item in number arrray in sum method.

console.log(sum.apply(null, numbers));
// expected output: 6