I am an undergraduate majoring in library science, and I am glad to answer your question. This is the classification number and call number, which is cataloged according to the China Library Classification. The number of each book is given according to the different subject contents of each book.

Its function for ordinary readers is to find books. When searching for books on the library website, the call number of this book will be displayed, and then you can go to the library to find this book according to the call number. For example, if this book is I 247+0428, just look for it on the shelf next to the library that says "I Literature".