It can mean pretty much anything "wow!" could mean. Usually utilized in the Southern US as an INTERJECTION, an exclamation of agreement; but also as surprise at the large quantity of something or severity of something.
Example:
Person #1: "Did that tornado swing by yer place last night?"
Person #2 : "Boy, howdy!"
howdy
howdy partner
it is a southern U.S. form of greeting
Fight
there's google translate for a reason... Anyway here's the answer: 你好 nǐ hǎo this can also mean; Hello, Hi, Hey, Howdy, greetings
Boy Howdy was created in 1990.
Since Howdy Doody didn't eat there was no worry about his doodie.
Jeffrey Steele
Hostile verbal expression.
Attaboy is an expression of admiration or encouragement to either a boy or a man.
brutus showed him what for. boy howdy!
Howdy hlufa.
Country expression of excitement, similar to yippee!, oh boy!, hurray!
howdy partner
Yes! and boy howdy is it fun!You can also die trying it.
It doesn't "mean" anything. It's just an expression of excitement.
Howdy Doody was a famous puppet on a television show. If you call someone Howdy Doody, you are basically implying that they look like him. Howdy doody was an unattractive ginger puppet who was covered in freckles and made to be the joke of the show. It was most popular among children. Howdy Doody was the poster child for ginger kids back in the 40's