A male
friend who is your right-hand
man. He's usually there for you, and is there to support you, and is very good at doing so in social situations. He's always there to offer you a wing.
The term originated from it's usage in aviation, and was then used to refer to a
man who would help his friend get his target woman. The wingman would distract the target woman's friend while his friend went in for the target.
"
Dutch is my wingman, he's always there for support."
"You were a
great wingman last night at that party, my
friend!"
"I need a wingman."