[WordShaker]

Spoiler:

Well, it may not seem like anything special, but you have to remember that Yuki is a humanoid interface who is unused to most "normal" human activities. The library, meaning the one Kyon and Yuki visited during that first meeting, where Kyon filled out the forms for a card for her to check out a book, had a profound effect on her. She's expressing her wish that she wants to go back to that library during the conversation on the computer, which is Yuki becoming more "human."