What is the pronoun for library?

Libraries are not people, so they don't have a pronoun in the same way that people do. You would use words like "it" or "that" to refer to a library, depending on the context.

For example:

* "The library is on the corner." (Here, "it" is the pronoun referring to the library.)

* "That library has a great collection of books." (Here, "that" is the pronoun referring to the library.)