Answer with Explanation:
Spain is known to have hot summers, thus, it is very easy for water to evaporate once exposed to direct heat source (such as the sun).
A fountain is being used in order to keep the garden's surrounding air temperature low by allowing the evaporation of water. One factor that speeds up the evaporation of water is the surface area. The water coming out of a fountain is in small quantities; however, it meets up with hot air in a large surface area. This allows faster evaporation, leading to an even greater cooling effect because heat is being transported immediately from the liquid state to the gaseous state. This is the reason why people often meet up in places where there's a fountain. It is not only aesthetically appealing but also provides comfort from the heat.