It's a gantry type 3 axis CNC with what amounts to a stupendously high-pressure pressure washer attached to it. The cutting head has a hopper that feeds a dry cutting abrasive in fine granular form (sand like or finer) into the water jet. The extreme pressure accelerates the water and abrasive to high impact velocity which cleanly cuts many materials including ceramics, glasses and very hard metals. A nice bonus is there is little heat input so you wont get warping or worry about annealing hard metals. Just under the cutting bed is a bath of water the jet terminates into. They do generate a little water mist during punch through but surprisingly is pretty dry around the machine. They make really nice clean cuts but require a lot of upkeep and the abrasive is a consumable you have to keep buying.

Ive seen one operating next to a plasma cutter (same CNC setup) in a fab shop and it was a night and day comparison. The plasma cutter was shooting sparks and embers everywhere while belching noxious smoke and the machine was filthy and covered in soot. Its more akin to welding. The benefit is they have less upkeep and consumables. Though plasma can not handle the variety of materials a water jet can.

A water jet sends an extremely high pressure thin jet of water that can precisely cut many materials.

https://en.m.wikipedia.org/wiki/Water_jet_cutter

Banksy?