It means it can't find a OS, so the system has no Operating system.
If you indeed have a Bondi system and it's the one I'm thinking of you have a system running a 233mhz processor and has a tray loading disk drive. Your OS options are limited to OS 8, OS 9, and OSX 10.1 I believe. I wouldn't do OSX 10 because it'll run terribly on that computer. Slot loading iMacs can do up to 10.4 but I don't think you have that one.