A "Widget" is what we call the visual building blocks of a dashboard in Signals. A Widget can either be a visualization of your data or it can be used to add text or images to your dashboard to provide context to viewers.
If you're working with multiple data-sources, you'll need to specify which data-source you want your widget to visualize when adding a new widget. We give data-sources and widgets corresponding color-codes to help keep track.
For more information see the Solutions article on creating a widget