Node.js - this a server like Apache that servers up your code. Node as npm which is a package manager.

Angular - this is your frontend, the html and what not. It's a single page application framework. It does not require node to run but makes it easier to build apps. Angular uses javascript to change out page content so you site only loads once and does refresh when you change pages.

Express - this is your backend code, it does require node. The frontend talks to Express via Rest calls, then express talks to the database and sends data back to the frontend.

Firebase - this is more or less a database but with some really cool realtime features.