A WordPress Widget is a small block that performs a specific function. You can add these widgets in sidebars also known as widget-ready areas on your web page.https://www.wpbeginner.com/glossary/widgets/
All widget areas can be configured in with the Live Preview tool at Appearance -> Customize -> Widgets.
This area houses the Search widget by default.
This area houses the Recent Posts widget by default.
Footer Sections 1-3
These sections house Text widgets by default and can be configured to include contact information etc. Text widgets do accept HTML for formatting.
Footer Section 4
This section includes the Simple Social Icons widget by default. This widget requires configuration if you would like to keep it.