When you see a chord, you have specific scale options. The book ranks these by consonance (sounds good) and dissonance (sounds tense).
The most probable meaning of "34" is that it refers to the book's price. Across multiple authoritative sources, including the publisher Carl Fischer's official website (listed at $34.99), SheetMusicPlus ($34.99), and other retailers ($34.99), the standard retail price for The Guitar Grimoire: Progressions & Improvisation is $34.99. The Guitar Grimoire Progressions And Improvisation Pdf 34