It can do stuff that running in your browser can not. Since electron runs both the client-side code and the server-side nodeJS you can communicate between the rendering engine and the back-end for tasks that a web browser alone wouldn't allow you to do, like accessing and navigating your local file system for example. Or if the app has a lot of assets and it needs to work offline, you can have the nodeJS backend download the files and encrypt them and have the front-end query the nodeJS and to get the decrypted assets and use the whole web app offline completely with a local database that you may sync with a webserver at some point later if or when internet connectivity is restored.

For most apps its overkill, but Electron and NodeJS can do pretty much anything a native app can do (just slower and while using a LOT more resources than a native app) but can be done entirely by someone experienced in web frontend development and nodeJS.