Reports is where the ! button your users press ends up.

Each row shows the post that was reported, its author, the reason given, who reported it and when, and the list is paged like the rest of the board. The reason is one of Spam, Misconduct or Illegal content. A board that nobody has reported anything on shows a message instead of an empty table.
The post links through to where it was posted. The reason on its own tells you how someone felt rather than what was written.
A user may report a given post once. Five rows against one post mean five people and not one person clicking five times.
The page reports and it does not act. What you do about a report is done elsewhere, from the author's profile or from Users, and a report stays listed afterwards rather than being cleared.
The page itself: Administration → Reports