quite close it means "his royal highness", 50% of the news on saudi tv 1 consists of this phrase...the repitition sounds funny lol
for example
sahibus sumoo il malakiyy al-ameer so and so, i.e. His Royal Highness Prince so and so.
@ bint abee, crown prince is waliyyul 3ahd.
but i dont think they use it with the king as well. they news casters just say khadimul haramain-ish-shareefain almalik ... :hmm: i could be remembering wrong
edit: next word: kuwayyis