IPA: //laɪˈbrɛəriən//
KK: /ˈlaɪˌbrɛrɪən/
A person who works in a library and helps people find and use information and books.
The librarian helped me locate the book I needed for my research.
Librarian → It is formed from "liber" (meaning book) and "-arian" (meaning one who). A librarian is one who works with books.
Think of someone who works with 'books' ('liber') — that's why a librarian is a person who manages books.