Too many triathlon books are incredibly technical with heart rate zones and advanced power metrics. These technical books have training plans that read like novels with 8 various sub workouts on a given day at all sorts of exact times and paces that are tough to get right.
I spent some time at a bookstore flipping through probably 20 different triathlon books and this was the one that stuck out to me as including some training plans that made sense to me and that I could actually follow. The plans are broken out into 3 levels from beginner to advanced so there is room to grow within a triathlon distance. There are also plans ranging from sprint triathlon to ironman so there is room to grow as you start to tackle longer races.
There is some good background information on each of the three disciplines as well as some good basic exercises and stretches you can do, but the real value is in the training plans.