I assume they're referring to Jorge Luis Borges's short story "The Library of Babel," which imagines an enormous library that has a book for every possible sequence of letters and punctuation, all of a certain length (a few hundred pages). The library therefore contains all useful books on any topic in any language (as long as it's covered by the alphabet), but also all useless or inaccurate ones, and of course a vast sea of gibberish. All the knowledge you could want is there, yet unattainable.
