A short story collection is a bunch of stories that are not too long like a whole book, but they are short like parts of a book that can be read quickly. Think about your favorite kids book that has lots of different stories in it. Each short story in the collection is like one of those stories in your book.
A person or group of people comes up with a lot of stories, and then they gather them all together and print them in one book. Each story is usually different from the other stories in the collection but they all have something in common.
You can read one short story at a time when you don't have a lot of time to read, or you can read several stories in a row if you have more time. Some short story collections are all about the same theme or type of story, like horror or romance stories. Others might have different genres mixed together like science fiction and fantasy.
Overall, a short story collection is a book with lots of stories that are short and can be read one at a time or all together, and they might have something in common.