Waterjets are amazing tools that are used to cut all kinds of materials. From soft foods to hard metals like steel. It is achieved by creating waterjets that are pushed through a narrow hole with enormous pressure and that's how the particles gain their speed. Other particles like sand is added to the water that does the actual abrasion. It's a great tool because it can't get dull and there is no overheating problem, soft materials won't stick a blade would need lubricant for that.
A video from youtube for your reference: How Water Jets Work.