Saved sections are sections that can be saved to your sections panel and be reused across the site. A saved section can only be used once on a page. Due to this, once a saved section has been used on a page, it will no longer appear in the sections panel while viewing that page. If you need to have another section matching that, you can use 'duplicate sections'.
Saved sections are connected to each other. If you make a change to one saved section, it changes that same section everywhere in the site it is used.
This help video shows you how to create and use saved sections:
When deleting a saved section from the saved sections panel, each section remains in each page, but will no longer be connected.