Alright kiddo, have you ever watched a movie or TV show with words at the bottom of the screen that tell you what the characters are saying? Those are subtitles. Same language subtitling is when those subtitles are in the same language as the audio you're listening to.
Why would we need subtitles if we can hear what the characters are saying, you might ask? Good question! Sometimes the people speaking have accents or speak really fast, so it might be hard for some people to understand what they're saying. Subtitles can help those people understand better. Plus, some people just prefer to read along with what they're hearing.
Now, same language subtitling is actually really helpful for people learning to read. See, when the words are on the screen as they're being spoken, it helps people match the written word to the sound they're hearing. This is kind of like learning to read the way you learn to speak - by hearing the sounds and matching them to the words.
And did you know that same language subtitling can even help make reading more fun? When you're watching a movie or show that you love and you can read the words on the screen along with it, it can make reading feel more like a game or a fun activity. Plus, you get to enjoy the story even more because you can understand everything that's going on - and that's always a good thing!