first off, you have to know what MIB you want to walk before you can know what the return tells you.
for instance, in the screenshot, the OIDs beginning with 1.3.6.1.2.1 can be found in the RFC-1213 MIB (or MIB2 if you prefer).
if you haven't done so already, I'd suggest downloading a MIB browser so you can load this MIB and see what the objects are.
now, specific to the sg500s, I do not have any experience with these but I believe that they have their own MIBs where you probably can find the objects you're looking for. These do not, to my knowledge, respond to the cisco specific MIBs. So you'd have to grab the specific MIBs for this platform and load it into a MIB browser to see what is available. You can usually find the list of supported MIBs in either the release notes or some other platform specific docs.