I suspect that at least some of these books will provide names and other information about families, especially those families that have been dispersed by the Holocaust.
The books that are expected to be uploaded will, according to NLI, include all of the library’s out-of-copyright, royalty-free books which have not yet been digitized. Around 45% of the books are written in Hebrew script, in Hebrew, Yiddish, Ladino, and other languages of the Jewish world. The rest of the works are in a variety of languages, including Latin, German, French, Arabic and Russian.
The books are transported from Jerusalem’s NLI to Google’s digitation center in Germany via Rotterdam in secured, climate-controlled shipping containers. With thousands of books being shipped, scanned and shipped back each month, the process is expected to be completed within two years.
You can read more in an article by Leon Sverdlov in The Jerusalem Post at: https://www.jpost.com/Israel-News/National-Library-of-Israel-uploads-120000-historic-books-online-607370.