This module enables the CodeSnippet plugin from CKEditor.com in your WYSIWYG. It includes the highlightjs library and all available styles for it. If you've ever wanted to drop code examples in your Drupal content and have it highlighted in a pretty format, this is for you. This project is available for Drupal 7 as WYSIWYG CodeSnippet. Since that project relies on WYSIWYG module, and this one only requires D8 core, it made sense to rename it.
Drupal 8 ships with CKEditor 4.5.x, so it depends on the ckeditor module from core.