Brew is a CLI-based package manager that helps you to manage and update all your development packages and automatically link them for you.
You should certainly use brew to install any language you are working with, particularly Node.js. Trying to install using nvm ("Node Version Manager," a method often suggested for OS X) can be at best tedious for someone who doesn't have much experience with the command line. You should also use it to install the AWS CLI when you get to that point.
Here is a great tutorial for installing brew.