" S'il te plaît, une pomme !"
S' = si = if
IL = impersonal subject of verb "plaît" = it
TE = indirect object of verb "plaît" to be placed before the verb = (to) you
PLAÎT = verb "plaire", construction with preposition "à": "plaire à" - conjugation agreeing with subject in 3rd person singular = please (construction with direct object, no preposition needed)