"You" in Korean
The words ‘너’ or ‘당신’ can translate to ‘you’ in English, but they are not commonly used unless necessary.
Instead of directly addressing someone as “you,” it’s more common to use the person’s name, title, or a term that reflects their relationship to you.
Don’t get me wrong, you can use 너 to your friends, and this is totally normal.
To colleagues, I would go with 씨 or 님
재준씨 or 준미님~
In the case of a stranger
선생님 or 사장님 is perfect
아이고 선생님~
아이고 사장님~
And lastly, we can use “저기요(hey)”