Ha! I can't believe I didn't think of coolant the first time I replied :bang:
Yes, a green, watery fluid will be from your cooling system. There are two large hoses at the front of the engine (one near the top, and one nearer the ground) which carry coolant between the engine block and the radiator. Like all rubber hoses they deteriorate over time and develop leaks.
When the system is at operating temperature, the entire system becomes pressurised, which will exacerbate any leaks, and can easily result in large amounts of fluid being lost quite quickly.
In terms of damage done, provided the engine hasn't severely overheated from a lack of coolant, you should be fine. The VT will sound an audible warning when the engine temp goes over about 115 degrees (normal operation is about 90 degrees), and even then if you pull over right away and top up the coolant you will be fine. If you keep driving and the engine gets too hot though, you can damage the internals.
Get the hose fixed ASAP, and while you're at it I'd check the condition of the heater tap and other coolant hoses which could be on the way out.