Okay, so first let's talk about languages. Do you know how we use words to talk to each other? Well, different groups of people might use different words or ways of talking. These different ways of talking are called "languages." For example, some people might speak Spanish, while others might speak Chinese.
Now, let's talk about the Austro-Tai languages. These are a group of languages that are spoken by people in Southeast Asia. The word "Austro" means "southern," and the word "Tai" refers to a specific group of people who speak the Tai language.
The Austro-Tai languages are interesting because they have some similarities in the way they are spoken. For example, they have similar grammar (the rules for putting words together to make sentences) and some similar vocabulary (the words that people use to talk about things).
Some people believe that this means that the Austro-Tai languages are related to each other, and that they might have all come from a common ancestor language a long time ago. Imagine all the Austro-Tai languages as cousins in a big family tree!
Another interesting thing about the Austro-Tai languages is that they are spoken in different countries, like Thailand, Vietnam, and Malaysia. That means that people who speak these languages might live in different places, but they can still understand each other a little bit because of the similarities in their language.
So, to sum it up, the Austro-Tai languages are a group of similar languages spoken in Southeast Asia. They are interesting because they might be related and because people who speak these languages in different countries can still understand each other somewhat.