Steam servers have backups like Minecraft servers: automatic every night, manual when you decide, kept for several days and timestamped to the minute.
Automatic backups
Every night, the server's entire volume is archived: world, settings, mods, everything that makes up your server. You do not need to schedule anything, the list fills up automatically.
Manual backups, and restoration
Before a major change, a major game update, a planned wipe or an unknown mod, trigger a manual backup: it freezes the exact state of the server at that moment. Restoration puts the volume back as it was, after the server has been stopped, players get the world as it was before, as if nothing had happened.
It is worth repeating the habit: two backup clicks before every risky action turn any mistake into a simple rollback.