Plugins give functionality to your website. Think of them as similar to an app on your smartphone that allows you to add new features to your website.
To add and activate a plugin from the WordPress repository is simple (See video below)
If you purchase a plugin from somewhere like Envato Market then you will be provided with a zip file. You can upload this to your dashboard from wherever you have the zip file saved. To do this click on Plugins/Add New and at the top of the page there is an “Upload Plugin” button
Before uploading a plugin, it is a good idea to read ratings and ensure a plugin is reasonably up to date.
An out of date or poorly coded plugin can make your site vulnerable to hackers.