If you're looking for a more detailed summary or analysis of S05E21, I'd be happy to try and help you find it. Alternatively, you can check out online resources such as IMDb, Wikipedia, or fan forums for more information.
In the context of media downloads, (MPEG-4 Audio) is an audio-only container format. While Young Sheldon is a visual television show usually found in video formats like MP4 or MKV, an M4A file for "S05E21" typically indicates: young sheldon s05e21 m4a