This would usually be a small-diameter fire-hose (not THAT small, fo course, but perhaps smaller than the very large hoses used by fire services, or even, than those commonly found on hose reels in large buildings.

'charged' normally means it has water in it all the time; i.e. you just have to open the valve on the end, and the jet will shoot out. This would be as distinct from a hose where you have to go all the way to the supply end to turn the water on, or worse still, have to actually connect it to the wall tap!