Bitcoin SV (Bitcoin Satoshi Vision, or BSV) is a cryptocurrency formed on November 15, 2018 by a hard fork from Bitcoin Cash. Bitcoin Satoshi Vision is the fourth largest cryptocurrency and has thus overtaken Bitcoin Cash (Source: Wikipedia).
Users who have secured their Bitcoin cash before the hard fork with a ledger hardware wallet automatically own the same amount of BSV as BCH.
BSV is not supported in Ledger Live. Instead, users can manage their BSV using the Bitcoin Cash app on their ledger device in conjunction with Electrum SV, as described below: https://electrumsv.io/.