请问第一张图片中的未备份的文档是否就是第二张图片中标出的文档？

Hi,

Yes, folder mentioned in your screenshot is the default Documents folder, which is not synced with OneDrive. It's located under your user profile directory, and its full path is C:\Users\%username%\Documents.

You can also right-click on the folder and click Properties to verify the folder size if needed.

Note:

When you sync that folder with OneDrive, the documents folder wlll point to C:\Users\%username%\OneDrive\Documents instead.