You use the Dell Remote Access Controller (iDRAC) in order to communicate with the RAID array and fetch information about the underlying physical volumes. Unlike traditional spinning disks, Solid State Disks (SSDs) of course have a limited write lifetime, so it's useful to be able to check what percentage of their lifespan remains so that you can proactively arrange replacement.
There's a full cheatsheet for Dell's iDRAC elsewhere, this page simply details how to check the remaining write endurance for your SSDs
racadm raid get pdisks -o -p state,RemainingRatedWriteEndurance
racadm raid get pdisks -o -p state,RemainingRatedWriteEndurance Disk.Bay.15:Enclosure.Internal.0-1:RAID.Integrated.1-1 State = Online RemainingRatedWriteEndurance = 100 %