What is Office Delve?
As written on support.office.com
Delve helps you discover the information that's likely to be most interesting to you right now - across Office 365. Find information about people - and through people - and help others find you.
You don't have to remember the title of a document or where it's stored. Delve shows you documents no matter where they're stored in OneDrive for Business or SharePoint in Office 365.
Delve never changes any permissions, so you'll only see documents that you already have access to. Other people will not see your private documents. Learn more about privacy.
Click someone’s name or picture anywhere in Delve to see documents they’re working on or to learn more about them.
When you find a document you’re interested in, add it as a favorite or to a board to easily get back to it later.
Search for people, documents, or boards.