what mean is let in JavaScript

Here's the lesson about it: https://www.sololearn.com/learn/406/?ref=app

Yexk let allows you to declare variables that are limited in scope to the block, statement, or expression on which it is used. This is unlike the var keyword, which defines a variable globally, or locally to an entire function regardless of block scope.

You should check out const as well because it is another way to declare a variable.

wow..thanks..

java script is based create web application