It takes 4.2 joules of energy to raise the temperature of 1 gram of water by 1°C. What heat of water is 4.2 joules/gram C?
This heat of water that you are referring to is the "specific heat of liquid water", or just "specific heat of water." Just remember that 4.2 J/g C is the specific heat of liquid water, and the specific heats of solid H2O and gaseous H2O are different.
I hope that helps!