What a debriding service does is download the torrent for you, and cache it on their servers. From there you can download it from their servers without ever "touching" the torrent itself. Common uses for it are with Stremio, to stream cached movie torrents directly from the debrid service's servers.
These services are also used to download from paywalled DDL websites, such as rapidgator, nitrodl, etc, so you do not need to wait 500 hours of 50kbps.