哈哈
Explanation
拟声词，形容笑声，常用来表示开心、愉快或轻松的情绪，可作状语修饰动词，也可作定语修饰名词。
"Haha" is an onomatopoeia used to describe laughter, often indicating happiness, joy, or a relaxed mood. It can function as an adverbial modifier for verbs or as an attributive modifier for nouns.
Examples
我还没进门就听到同学们哈哈的声音了。
I heard the students' "haha" laughter before I even entered the room.
听了他的话，我们都哈哈地笑了起来。
After hearing what he said, we all started laughing "haha".