Explanation
Box 1: Review
Review - The draft version of the article is sent to reviewers to approve or reject.
Mark a knowledge article for review
To ensure that the content you've created is accurate, have someone review it.
You can mark an article for review or directly assign it to a specific person or queue. When you mark an article for review, it starts appearing in the knowledge manager's dashboard. The knowledge manager can then assign the article to specific team members or a queue for review.
Box 2: Published
When you approve the content of an article, it means that the content is ready to be consumed by other customer service reps, and also ready to be published.
On the Business process bar, in the Review stage, in the Review field, select Approve.
The article is now ready to be published.
Box 3: Draft
Draft - The article is in the process of being created.
Note: A versioned knowledge article in the Draft state can be modified only by the author or reviser with the contribute access to the knowledge base, owner of a knowledge base, users with the admin and knowledge_admin role, and ownership group members, if ownership group is added to the article.
Reference:
https://docs.microsoft.com/en-us/dynamics365/customer-service/customer-service-hub-user-guide-knowledge-ar