is the car overheating, if so check thermostat first, if thats fine either coolant pipe leak or blown cylinder head gasket. have you had white smoke coming out of your exhaust at all before you noticed it in the engine bay. when the water /anti freeze and fuel mix this will cause white smoke. thermostat and pipe replacement are relatively easy to replace and fix, head gasket if it is (hopefully it isn’t) is a lot harder, there is checks for this but I'd check other components first to rule out any easy fixes.