As others have suggested, Wine Folly is a great starting point and it's where I learned a lot at the beginning of my wine journey (by no means am I an expert or even close). Another book may also be Kevin Zraly Windows of the World Complete Wine Course. And then the larger, denser books (Wine Bible, World Atlas of Wine, among many, many others).
Also, I've been taking a course on Coursera (not wine related) but out of curiosity, decided to search wine and this course came up;
Wine Tasting: Sensory Techniques for Wine Analysis
https://www.coursera.org/learn/wine
Probably worth looking into! It's free! I'm going to likely take it haha :)