Elementor is a visual page builder plugin for WordPress enabling the creation of web pages in a live, visual way. It replaces the basic WordPress editor with a live frontend editor, so you can create complex layouts visually, and design your website live, without having to switch between the editor and the preview mode.
The free version of Elementor is bundled and required for Jupiter X but purchasing the Elementor Pro is optional and Jupiter X works perfectly fine without the Elementor Pro. However we encourage you to purchase the Pro version of this plugin, if you want to have much more cool features like: Theme Builder, more Widgets, new Elementor templates, more Integration, adding Custom Fonts, etc., to build a better website.
Please check this to see all Elementor's features.