It can show annoyance, excitement, surprise, and a range of thoughts and feelings depending on the context and the rest of the sentence.
Lindy: Dang that boy is hot!
Taryn: He sure is! I might ask him for his number.
Lindy: Hands off bitch, I saw him first!
Taryn: Dang you’re touchy! Chill!
It can also be used as an adjective, as in “get your dang hands off of me”. It is a more polite way to say damn, and as well as being heard in general speech is also very popular in cartoons.
This Twitter user expreses disappointment in Debonairs' flair: