When you log in to a WordPress site, you will see boxes full of information. These are called “Dashboard Widgets”.
You will probably see a “Welcome to WordPress!” widget with lots of useful links. There's also a “WordPress Events and News” widget with official updates. There's an “At a Glance” widget so you can quickly see key statistics for your site.
Those are only some of the default widgets. And when you add plugins, they will also add extra widgets. In the image below, you can see a widget called “Easy Digital Downloads Sales” which comes from a plugin.