Meaning of this? (오~)

[Idolbunny🐰]

I have a Korean friend that I did recently, sometimes we chat and we do it in Korean usually since I'm learning the language.
sometimes she put together sentences or I show her exercises that I do to which she responds sometimes things like: "오~ 잘 했어요" the meaning of it its "well done" (잘했어요) but I don't understand what Is 오~ yeah i know that is translated as "oh" but i don't understand What's the meaning since I never saw that word. (오~)
I would be very grateful if you could help me !!! (✿^‿^)

 

[OppaIsTrash]

your friend would probably explain it better, but i'm guessing it's just that, an 'oh'.

 

[BiasWreck]

It is literally just "oh" lol

she's like "Oh~ good job" because yes