This scope lets an app "Upload, edit, and delete files as your slack app"
This OAuth permission scope works with these Web API methods.
files.comments.delete - Deletes an existing comment on a file.files.delete - Deletes a file.files.revokePublicURL - Revokes public/external sharing access for a filefiles.sharedPublicURL - Enables a file for public/external sharing.files.upload - Uploads or creates a file.