Meanings
Deuteronomy 32:10, where it translates Biblical Hebrew אִישׁוֹן עֵינוֹ (ʾîšôn ʿênô, literally “the pupil of his eye”)[1]; from Middle English appel of the eyȝe, appel of þe ye (“eyeball; the visible part of the eye; pupil”), a dissimilated variant of Middle English ij appel (literally “eye-apple”). Compare English eye-apple.
How to pronounce "apple of someone's eye":
AU
A favourite, a particular preference, or a loved one; the object of somebody's affections.
Example: "Sara was never the same after losing her daughter, the apple of her eye."