Hello, baby. How to say it in English?

The most direct English expression: "Hello, baby."

Greetings in different contexts can be expressed in different ways, such as:

Hello, sweetheart?

The saying in the black media environment is: What's the matter, man?

Americans simply say: Hello (Hi).

Therefore, when using greetings, we should pay attention to the context and the speaker, and adjust the expression appropriately to make the language expression more authentic.