Bulk metadata editing is a new SharePoint Online feature in Office 365. We’ll begin rolling this feature out in the next few days.
How does this affect me?
This feature allows you to edit the metadata of several items at once by selecting those items in the modern list view, and using the details pane to edit their metadata.
We’ll be gradually rolling this out to Targeted Release customers on January 17th, and the roll out will be completed by the end of January.
There is nothing you need to do to prepare for this change. Please click Additional Information to learn more.