What is hahahaha?

It seems like you're referring to "hahahaha," which is a way people express laughter in written form. It's commonly used in digital communication to convey amusement or laughter. The repetition of "ha" can vary, such as "haha," "hahaha," or even a longer version like "hahahahaha," with the length often indicating the strength of the laughter. This expression is universal across many languages and is widely used in text messaging, social media, and online chats. It serves as a quick and informal way to show that something is funny.