Oye

A friend of mine send me a text "sí estoy bien oye", I know it says yes I'm good, but I'm confused by oye. I always thought it meant hey. I have never seen it at the end of the sentence. Just not sure if it has some other meaning, or if she is trying to say something else.

The only situations I've heard oye in the end (and as I myself use it) is when the person speaking is angry, disturbed by something, for example:

I'm ok, man, stop asking me the same question over and over again!

Your sentence also starts with Sí which makes me think that there was a question before it, something like:
"¿Estás seguro que estás bien?" - "Are you sure you're OK?"
"Sí estoy bien oye" - "Yes I´m sure, man!"

Thank you that helps. I have just only seen it at the beginning of a sentence. I am trying to learn spanish, and online translation is not very helpful sometimes.