Basically anything that has been or could be said and is under 3200 characters is in the library of babel, that means
nuclear launch codes
the cure for every disease
it even has the description of everyone's birth
the only problem is you cant ask "what's the cure for cancer" and have it pulled up, because the library itself doesn't know
this clip of a Vsauce video explains more of how it works and how it isnt bullstuff
https://youtu.be/GDrBIKOR01c?t=17m10sThe Library of Babel