What is what does hun mean in texting?

In texting, "hun" is generally used as a term of endearment. It's a shortened, casual version of "honey".

• It can be used platonically between friends, especially women. Platonically
• It can be used romantically between partners. Romantically
• It can sometimes be used sarcastically or condescendingly, depending on context and tone. It is important to know context of the conversation. Context

The meaning is usually inferred from the relationship between the texters and the overall conversation.