Foxglove's an amazing, regal spring biennial. Biennials, unlike the more common perennials and annuals, need two seasons to complete its life cycle (another popular biennial is the common pansy).
If the name Digitalis sounds familiar, you may be thinking of the heart drug digitalis. Digitalis contains cardiac glycoside digitoxin, which is used to treat congestive heart failure -- it essentially makes the heart beat stronger and faster. However, if you have a bad ticker, don't go gnawing on the plant as-is. Foxglove is highly toxic when taken in anything other than the smallest of quantities, or in its basic form.
Digitalis obviously refers to one's digits, presumably because the individual blossoms would fit over one's finger easily enough. This also accounts for the less-common name, witch's bells, as witches wore these blossoms as little finger-gloves (I suspect the poisonous nature of this plant could have something to do with witches using it, too). Finally, it's not a long shot to guess that the common name foxglove refers to the blossoms easily fitting over a fox's paws as well.
Foxglove used to belong in the Scrophulariaceae (snapdragon or figwort) family, but has recently been moved to the Plantaginaceae (plantain) family. Most people with a lawn probably shudder at the word plantain, as Plantago a tenacious lawn weed. Similarly, in areas out west, foxglove is an invasive wildflower.
An aside: The plantain family does not include the tropical banana-like plantain, Musa. Musa, incidentally, is also the genus name for mouse. The fact that these plants share the common name plantain is a great example of how common names can get pretty confusing, pretty fast.