Okay, I'll try to explain this to you like you're five!
So imagine you have a book report to do, and you have to list all the books you read for it. This list of books is called a bibliography.
Now think about how sometimes you talk in one language (like English) and then switch to another language (like Spanish) without even realizing it. This is called code-switching.
So a bibliography of code-switching is like a list of all the books and articles that people have written about code-switching. People study code-switching to understand how and why people use different languages in different situations.
Some people might be interested in how bilingual people switch between languages without even noticing it, while others might be interested in how code-switching is used in literature or pop culture.
So, to sum it up, a bibliography of code-switching is a list of resources that people can use to learn more about code-switching and why people use multiple languages.