The code creates an array of strings and a new set. The new set is a merged copy of the arrays arr1 and arr2.
//ref: https://youtu.be/bbnkAV12Tig
const arr1 = ['a','b','c'];
const arr2 = ['c','d','e'];
const merged = [...arr1,...arr2];
const mergedSet = [...new Set([...arr1,...arr2])];