Okay kiddo, let me explain what an ergative-absolutive language means in a simple way.
When we talk about actions and the people or things that are involved in them, we use a type of language called grammar. In some languages, like English, people use a subject-verb-object sentence structure to show who did the action, what they did, and who or what they did it to. For example, "I kicked the ball" has "I" as the subject - the person doing the action, "kicked" as the verb - the action being done, and "the ball" as the object - what the action was done to.
In an ergative-absolutive language, the grammar works a bit differently. Instead of the subject being the person or thing doing the action, like in English, the subject is the person or thing that is affected by the action. So instead of "I kicked the ball," in an ergative-absolutive language, it would be more like "The ball was kicked by me."
In an ergative-absolutive language, the word that takes the same form as the subject of a sentence in English is called the absolutive, and the word that takes the same form as the object of a sentence in English is called the ergative. It's just a different way of thinking about how sentences are structured!
I hope that helps you understand what an ergative-absolutive language is!