Not in the sense that it's not there, or that there's a second language that the JS interprets. But when you open emacs without specifying a file to open you are dropped into a buffer called *scratch* which lets you directly execute elisp code. It really is a central part of the experience of using emacs. Similarly, your configuration file(s) are written in elisp, versus often a subset of JavaScript (perhaps JSON) used in JavaScript-based editors. And you're not just supplying configuration data, but extending the program.
And then there's completeness. While emacs has parts written in C, that portion really exists to enable elisp. Essentially every capability of the editor is directly reachable through lisp. The same doesn't seem (or at least feel) true of JavaScript-based editors I've tried. In those, it often feels more like the creators have selected a portion of the internals to expose to users, but it's more the minimal amount needed rather than the maximal amount possible that emacs strives for.
EDIT: I've finally figured out how to insert an asterisk around a word on HN without needing spaces. Is this documented anywhere? Just use double asterisks on either end like
**foo**
Turns out this is in the FAQ, it's been a while since I looked at the formatting part of that so I guess it changed since 10 years or so ago or I'd forgotten.