Many Arduino books assume you know at least a bit about electronics. Learn Electronics With Arduino by artist Jody Culkin and Eric Hagan is written for people who want to learn about electronics but are complete electronics newbies.
The 384 page book covers basic electronics equations, components, and circuits, as well as how to use and program an Arduino microcontroller. It has many step-by-step instructions for projects and the authors do an especially good job of explaining each line of programming code used in the examples. You'll also learn how to use a solderless breadboard and a multimeter. It's full-color with lots of photos and clear illustrations.