what is the meaning of spread operator in javascript code example

Example 1: spread operator javascript

const parts = ['shoulders', 'knees']; 
const lyrics = ['head', ...parts, 'and', 'toes']; 
//  ["head", "shoulders", "knees", "and", "toes"]

Example 2: spread operator javascript

[a, b, ...objIteravel] = [1, 2, 3, 4, 5];