It's a general purpose programming language, assuming Common Lisp.
There are many variants though and you'll find some for very specific situations too. The beauty is that it can easily break out of the comfort zone it was made for, so elisp (from the Emacs editor) allows you to do all sorts of other stuff such as browsing the web or handling your mails.
When you get comfortable with the strange naming, lisps can become a safe and fun place to play. Many variants have all sorts of escape hatches when you're getting yourself in trouble which makes a bunch of plot-twist requirements changes very feasible to tackle.
Anyhow, we use Common Lisp for some web services which see much reuse across apps.