This expresses a exothermic dissolution into water.
Solution is the homogeneous mixture of two or more substances where is liquid which is more in concentration than the other called solvent, where is the other one is less in concentration than the previous called solute. The formation of solution requires three types of bond breaking or formation:
A. Breaking of solute solute bonds.
B. Breaking of solvent solvent interaction.
C. Formation of solvent solute interaction.
The first two processes requires energy which is needed to be supplied from outside hence endothermic where as the other step that is the formation of solvent solute interaction is is giving out energy to the system, hence exothermic.
Is the collective value of the first two processes is more than the last process then more energy is required by the system to break bonds rather than forming one. So the process becomes endothermic in total. On the other hand if the solvent solute interaction releases more energy than the two processes then the whole process becomes exothermic. This is what is is discussed in the question.