When a girl says "heyyy", what does that mean?

That’s a really complicated question.

Usually hey just means hello, but that’s only when normal human beings say it. When a GIRL says it, it can mean a ton of things, depending on how she says it.

It could mean, hello, obviously.

It could also mean, I like you, do you like me?

It could also mean, I love you and want to marry you and have your kids and hope you never cheat on me because if you do, I’ll snap off your penis!

It could also mean, higgs boson particle didn’t really prove anything as far as the true nature of the universe goes.

Or it could mean, blah… blah… blah…