Definition:A way to say 'Bravo!' or 'Good job!' by slapping someone's hand in the air; to congratulate someone.

表示喝彩或者干得好，动作就是在空中与别人击掌，以此来恭喜别人。

Example:

1) Nice shot! High five, dude!

好球，让我们来high five。

2)They exchanged a high five and went on with their own business.

他们相互击掌打过招呼后，便继续各行其事。