El niño del segundo piso. a. huye b. cayó c. crecieron

El niño cayó del segundo piso.

cayó is the conjugation of the irregular verb caer for the third person singular in the preterite tense. The preterite tense is one of two simple past tenses. It is used to describe actions that took place or were completed at a certain point in the past. So, this sentence means:

The boy fell from the second floor.

when you are going to explain a procedure,   the first thing to do is to name the parts or the apparatus you are going to describe in terms of how it or they function. also it is important to know who is going to operate it and the abilities this man/woman requires to manage it.

uhm what exactly is the question?