The Kelvin rating refers to the spectrum of radiation (AKA light) given off by a black body at that temperature....basically a lot of physics jargon.
As meegosh said, what kind of bulbs you use is dependent on the kind of tank you have, with refinements for preference. For a fish only tank (fresh or salt) or a FOWLR, any bulbs will do. For a planted FW tank, 5500-10000K bulbs will work. The lower the number, the warmer the color put out by the lamp. For reef tanks, bulbs with Kelvin ratings higher than 10000K are needed, usually along with some actinic (blue) bulbs, as these replicate the light spectrum at deeper depths on the reef where many of the corals common to aquaria are found.
From what I've seen, most Home Depot (ie household) bulbs are less than 5000K, most around 2100-3300K. House bulbs are much more "yellow" than the bulbs needed to grow plants or corals. If you stuck a 10000K bulb in your living room lamps, you'd think you were in an operating room - the light is very white and not very "homey" feeling. You may find some plant bulbs in Home Depot that have appropriate ratings.