System Operator. The In non-nerd speak, it was the guy who owned and ran the local public fourms site on his computer that you connected to with your computer. Lemmys instance admins are usually sysops for example as they have root/hw access to the computer that the Lemmy instance software runs on. This person is talking about an admin of a local fourm site early internet users used before centralized social media like MySpace and Facebook made Bulletin Board Systems (BBS) irrelevant.