When water is heated to a temperature ‘X’, it gets converted into steam at temperature ‘X’ by a process called ‘R’ and when steam at temperature ‘X’ is cooled, it gets reconverted into liquid at the same temperature ‘X’ by a process called ‘S’. What is the name of the energy absorbed during the process ‘R’?

The amount of heat required to convert 1kg of liquid into its vapour is called latent heat of vapourisation its value for water is 2260 kJ/kg.

We remember that at constant temperature phase change is happened for a substance. In that case more amount of heat energy is absorbed by the substance. 

Ex: $\text{Ice}\left(s\right)\stackrel{\text{Latent\hspace{0.17em}heat of fusion}}{\rightleftharpoons }\text{water}\left(l\right)$

$\text{Water}\left(l\right)\stackrel{\text{Latent\hspace{0.17em}heat of vaporization}}{\rightleftharpoons }\text{water(vap)}$