Not a book, but for a technical overview of exposure I recommend the wikipedia entry on Exposure value.
Briefly, you have some level of light in the scene, called LV (light value or luminance value), and a combination of camera settings - shutter speed, aperture and ISO - called EV (exposure value).
They are measured on the same scale, and when LV in the scene equals EV on the camera we have a correct exposure.
This is "correct exposure" in the rather narrow technical sense of making a gray card show up as 18% gray in the image. This is how camera light meters work: They assume that you want everything in the scene to average out to 18% gray, and will give a night photo the same average brightness as a day photo if you let them.
You will probably want to know about dynamic range as well, the ratio between the brightest and darkest luminance a sensor can capture in a single exposure. Many other fields measure dynamic range in dB (log 10 scale), while in photography we most commonly use stops (1 stop = 1 EV, log 2 scale).
Many scenes will have a higher dynamic range than the sensor can capture; then you'll need to decide which parts you are willing to sacrifice.
Alternatively, look into more advanced topics like HDR or exposure fusion, which combine several pictures of the same scene, taken with different EV settings, into a single image.
The Zone System is based on EV and dynamic range: You pick a single spot in your scene and decide how bright or dark you want it to appear in the photo, and adjust the EV from the light meter reading accordingly.
The question "What is Ansel Adams' Zone System" has a nice overview with example pictures.
As far as the technical aspects of exposure go, that's pretty much it.
There are also various effects of choosing different shutter speed/aperture/ISO combinations for the same exposure, but those are different topics. (Primary keywords: Motion blur, depth of field and high-ISO noise.)