What does "Service Ride Control" mean?

I have an 03 yukon xl Denali with 97K miles and 22" rims. I hear it has something to do with the shocks and air compressor, when I turn on the truck i hear the air compressor pumping, I'm thinking somethings wrong with the shocks. About 2 days ago i got the "service Ride control" message and im trying to figure out what exactly what that means.