While no amount of reading will teach you how to sail, books can help you learn some things about sailing and a lot about different kinds of sailboats, what they're good for, and at least as important, what particular sailboats are not good for.
I am in the middle of buying a sailboat. I have started buying one, have looked at some boats and have a fairly good idea what I want. I have read a fair number of books along the way.
Before buying a sailboat, I assume that you know something about sailing. If you haven't been sailing, don't buy a boat. Instead, go sailing with a friend. If you're like me and don't know anyone locally who sails, take a sailing class and rent a boat from a local sailing club. You learn a lot about what you like and don't like while sailing. Your personal preferences will have a big effect on the sailboat you want to buy.
The links below are to pages on sailing generally and on buying a sailboat. I discuss some books below on sailing because you can make a better choice of sailboat if you know more about sailing. Even though you can't learn how to sail just reading books, it would have been hard for me to learn to sail as well as I can without ever reading a book about sailing.
magazines
Magazines are a ready source of information. A magazine article generally conveys basic information in a concise form. It is possible to learn quite a bit reading magazines. Sometime what you learn is that you disagree with the article's author, but that is fine too. Articles in sailing magazines tend to be reasonably short with colorful pictures. Colorful pictures are very nice on a bleak Winter day.
Sailing magazines include reviews of boats, new mostly but older ones in other magazines. They also include stories about sailing trips, charters, misadventures, long-term cruises, racing, and a multitude of other topics. I would be surprised if you decided to buy a sailboat and bought one without reading a single sailing magazine. It is possible, but it seems improbable.
I read a couple of sailing magazines regularly and have sampled quite a few. My page on Sailing magazines provides an overview of the ones that I have read at least a few times. It may help you decide what's worthwhile to read.
learning to sail
If you're like me, you may not know a lot about sailing when you start thinking about buying a boat and going sailing. If so, you may want to pick up a few books on sailing, weather, rules of the road and a myriad of other things. My page on Learning to sail summarizes information about some books that I have found particularly useful.
books to help buying a boat
Choosing a sailboat is hard. Worse, choosing books to help choose a sailboat is almost as hard as choosing a sailboat.
Which books are useful for learning what? My page on Books to help buying a sailboat summarizes some of what can be learned from various books.
postscript
Now you may wonder: How many books has he read? Actually I've read quite a few more. I read a lot; it's an occupational hazard of being a professor. In these summaries, I have mentioned the books likely to be useful to someone thinking about buying a boat. I know that I have found them useful.
I wouldn't suggest to anyone that they read them all. I've tried to provide enough information about each so you can tell whether a book or magazine might be useful to you.