This is the 19112th most frequent Korean word.
아이폰을
"아이폰을" means "iPhone" (object form).
In this sentence, '아이폰을' is the direct object of the verb '사용합니다', meaning 'to use'.
나는 아이폰을 사용합니다.
I use the iPhone.
Here, '아이폰을' is the direct object of the verb '잃어버렸어요', meaning 'to lose'.
아이폰을 잃어버렸어요.
I lost my iPhone.
In this case, '아이폰을' is the direct object of the verb '줬어요', which means 'to give'.