Dear sci, can someone here explain this quote from wikipedia, under 'Granite'

"The melting temperature of dry granite at ambient pressure is 1215–1260 °C (2219–2300 °F); it is strongly reduced in the presence of water, down to 650 °C at a few kBar pressure."

WHat do they mean by 'the presence of water'? The presence of water molecules within the rock, which got there as it formed or can you somehow.. idk, soak granite in water to lower it's melting temperature or what?