What is meant by MEAN stack?

Question

I have heard about MEAN Stack. What do they do and how long will it take one to learn them all.

Answer 1

Don't know about the how long part, guess it differs between people, but this page explains MEAN and MERN pretty clearly

https://medium.com/datadriveninvestor/most-popular-technology-stack-to-choose-from-full-stack-vs-mean-stack-vs-mern-stack-in-2019-d12c0a17439a

Answer 2

MEAN is a group of software development components for web applications, the acronym includes:
MongoDB - a NOSQL database
Express.js - an application server
Angular.js - a frontend framework
Node.js - a javascript runtime on server side.

With the MEAN stack you can use Javascript in all parts of your application.
SL lesson:
https://www.sololearn.com/learn/1017/?ref=app