Suspension. I think it means it suspects your are bottomed out on something and Extended Mode is available. If you put your foot on the brake and push up on the suspension switch, it should give you another couple of inches of lift. In theory, that would allow you to drive off whenever you are snagged on. There is another mode also, called Super Extended Mode. I forget the actual numbers, but it’s something like a total of 4” of lift above standard raised offroad height. It makes your rig look like it’s on stilts, but there is Zero compliance left in the shocks. It’s quite rigid in ride quality at that height!