check chassis fan and power supply status?

The '| grep -iA 9 "Chassis Fan Status"' part says 'show any line containing "Chassis Fan Status" (case-insensitive) and the 9 lines after that'. It's used here to only show the part of the output that you're actually interested in, rather than all the other "show sys hardware" guff as well.

It's useful in examples like this to trim output (especially with the amount of stuff on a Viprion) and avoid including serial numbers or other identifying data. It does mean you need to know how many lines to include (which varies - a Viprion 4400 might have eight fans and four PSUs, whereas a smaller appliance might only have three fans and two PSUs), so for your own use, you can just leave it out if you're not sure.