Reddit mentions of Music in Theory and Practice Volume 1

There are introduction to music theory books / classes that are designed for people with zero knowledge. I took such a class before I took the serious class. It generally teaches you the most basic stuff like how to understand music staff notation, which is a requirement to use a proper music theory book. You don't have to be a proficient sight reader, but you have to at least know how to figure out what the notes and chords are on the staff. An introductory book will also introduce basic things like the diatonic scale, intervals, key signatures, the circle of fifths etc...The book I used after the first linked one was this. Those are kind of pricey, but if you look for used copies or older edition used copies on Amazon you can frequently find one in near perfect condition for like $20. Read the other comments I added to my original response hehe, as they are pretty important to consider. Those books are designed for class settings, but if you have good reading comprehension, it's possible to do it on your own.

benward/saker