what is ... in javascript

| <= | less than or equal to |	x <= 8 | true |

function sum(...numbers) {
	return numbers.reduce((accumulator, current) => {
		return accumulator += current;
	});
};
 
sum(1,2) // 3
sum(1,2,3,4,5) // 15

const adrian = {
  fullName: 'Adrian Oprea',
  occupation: 'Software developer',
  age: 31,
  website: 'https://oprea.rocks'
};

const bill = {
  ...adrian,
  fullName: 'Bill Gates',
  website: 'https://microsoft.com'
};