Emacs is a highly configurable text editor with wide support and a long history. Some of the things Emacs is good at:

And those are just a few things. Emacs can do anything you want, if you're willing to put in the work to configure it. Or pilfer other people's configurations. That works too. Think of Emacs like a build-your-own editor kit, with a really basic editor available to you out-of-the-box.

How do I configure Emacs?

You can look at the sections on this wiki that relate to what you want to do, or look on the Emacs Stack Exchange or the Emacs Wiki.