It doesn't really "mean" anything. It is not exactly translatable. It EXPRESSES various types of EMOTIONS in reaction to something perceived. Sometimes the emotion is disappointment or exasperation. EX: "You did really well on the exam but others did better" - "Awhhh! Man!" EX: "Your car was just hit by a bus" - "Awwh! Man!" Sometimes "Awwwww" (with varying numbers of "w"s) expresses a different emotion, such as "That is so sweet/cute". EX: "You see a tiny kitten playing with a puppy" - "Awwwwww!"

It's an interjection that's used to express either disappointment or contempt. Usually people online would write "awww" with no "h" at the end but if you wrote "awwwhh" most people would understand.

not sure what exactly is meaning of it.

I saw it everywhere, but not sure what is exactly meaning.

Context, please? Where did you see this? People often say "awwwww" to respond to something cute (like a baby or an animal), but I've never seen it spelled like that.