There are a few different things that will appear in the “Needs Review” page.
The example in your screenshot is a post that needs approval. You can see the nature of the review record in the upper left (“Queued Post” in this case) The reason the post requires approval is displayed at the bottom of the record. In this case it was “The poster typed in their post suspiciously fast.” There is also a link pointing to the setting in your admin panel that would allow you to adjust the rules that determine which posts will require approval. Clicking the “Approve” button will allow the post to go through, whereas clicking the “Reject” button will delete the post. The other two buttons should be fairly self-explanatory.
User submitted flags will give you different button options. You can read more about them here: Discourse Moderation Guide
If you go to ryanalex’s profile, there’s a button labeled “Admin” This will take you to the user admin page where you can delete the user. When deleting a user from the review queue, you will delete all of their posts, including the one that’s shown in the queue.
If there’s anything that’s still unclear, let us know and we’ll try to improve our documentation.