Coolant leak? It means either a hose, the radiator, coolant reservoir or water pump is leaking and or failed and you should repair ASAP and not drive far so you don't overheat the engine.
How do i know which of those is whats wrong?
You have to open the hood and see where it leaking from and or you can do a pressure test on the system. It sounds like your not versed in working on cars, so best to have a mechanic inspect it and repair.
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