When you click Files in the AdminCP the first page you see is the Attachments screen which lists all file attachments Suite-wide.
File attachments on this screen only include those files attached to a post-field. This would be any attached file to any content that members type in the editor. It does not include application-specific files such as Gallery images, Downloads files, member photos, and so on.
Attachment List
You can quickly delete attachments on this screen or use the magnifying glass icon to see where a certain attachment is being referenced. Members can upload ones but embed an attachment in multiple posts so it's a useful way to see how a member is using their attachments.
Attachment Search
You can also quick search a file name or open up advanced search options. Note that downloads do not work for images as they are not downloaded but simply viewed in the post itself.