All of the visual and hierarchical information abstracted away for visual users in a website that conveys information.

Abstracted visual semantic clues:

  * the type of data in said div

  * the indentation

  * the typography

  * the animations

the layout on the page

  * the interactivity
 with touch and mouse and keyboard events

These clues arw completely lost to blind users. Semantic attributes can help build up that hierarchical information for non-visual users. And yes, the name of a division is semantic information. It serves the purpose of defining an identifier for a section of a document, much like the title of the list above.