yur'sili
He will send down
V – 3rd person masculine singular (form IV) imperfect verb, jussive mood
Root Link: ر س ل
l-samāa
(rain from) the sky
DET – determiner prefix al + N – accusative feminine noun
Root Link: س م و
ʿalaykum
upon you
P – preposition + PRON – 2nd person masculine plural possessive pronoun kum
Root Link: ع ل ى