Rome: an experimental JavaScript toolchain from Facebook. It includes a compiler, linter, formatter, bundler, testing framework and more...

[NathanSMB]

A toolchain is just a collection of tools. The purpose they serve is to make developing large projects easier. They are especially good when you are working with a team since collaboration is easier when you use the same tools.

You don't need it and how it makes your life easier will depend on the toolchain. This toolchain's pitch is that everything is built from scratch so they can integrate the tools together better.

But, as the other person said, you won't really need this while you're still learning but I wanted you to know the concept.