These bulbs are the same size and shape as your standard old-fashioned incandescent light bulbs. They have what's called an "Edison" style screw-in base, which is what you are most likely used to; it is standard on bulbs designed to screw into standard household lamps and fixtures.
These can be used anywhere you would use an incandescent bulb with the same screw-in base. They consume roughly one eighth the power of an equivalent incandescent bulb, and they generate very little heat. If you run an AC in the warmer months, an incandescent light bulb is a double whammy. Pay for the electricity to power the bulb, then pay for the electricity to run the AC and remove all that generated heat that comes from the bulb. In this scenario, LED bulbs are actually roughly double their nominal savings!
This is a box of 24 bulbs, for about a dollar per bulb. Compare that to prices at your local grocery store or hardware store; it's a real bargain.