Why is the heat content reported in kJ/moles NaOH?

we did a lab where we put random metals that were really hot into a cup of water that was at stp. it also had some other chemicals in it like HCl (hydrochloric acid) and NaOH (sodium hydroxide) we calculated the specific heat capacity by finding the number of joules that was used to make the water warmer and the metal cooler. this helped us find which metal it was. OK GO!