This is a list of unpublished comments. There are multiple reasons a comment may become unpublished, but a really common one is that 3 logged-in site users flagged the comment as spam. This list is to provide Admins a spot to more easily see potential spam comments and their authors.
Un-published comments are invisible to "normal" users. For Admins' views an unpublished comment will have a slightly darker background than a published one, and will also have a 1 pixel red border around it.
If you decide a comment is not actually spam, simply click its Edit link, reset its Status to "Published", and save (optional: uncheck "Send subscriptions notifications"). After that it will no longer be affected by the Report Spam function.