It will install a default Java kernel (currently JJava) which is then available locally on your computer. This can then be used in your local Jupyter install or via editors that support jupyter ...

JupyterLab preview extension Voilà provides a JupyterLab extension that displays a Voilà preview of your Notebook in a side-pane. Starting with JupyterLab 3.0, the extension is automatically installed ...