what does pop mean in javascript code example

Example 1: js array.pop

let cats = ['Bob', 'Willy', 'Mini'];

cats.pop(); // ['Bob', 'Willy']

Example 2: js array.pop

let cats = ['Bob'];

cats.unshift('Willy'); // ['Willy', 'Bob']

cats.unshift('Puff', 'George'); // ['Puff', 'George', 'Willy', 'Bob']