EVs refers to 'Effort Values' which increase the Pokemon's stats depending on how many EVs for that stat you have. EVs are obtained by defeating a pokemon in battle and are distributed similarly to EXP, only that EVs are solely dependent on the species and not the level. When the opponent is defeated each pokemon involved in the battel (including pokemon with EXP Share) will often recieve 1-4 EVs for one specific stat with basic pokemon giving 1 EV, Stage 1 giving 2, and Stage 2 giving 3 or 4 (There are many exceptions to this rule, for instance Unown gives you 1 EV for two different stats, Attack and Special Attack) For a list of EVs I recommend checking out Serebii's Pokedex, the dark grey buttons will show which pokemon give how many EVs for the stat you choose. For every 4 EVs in the stat the pokemon will recieve one point for that stat. For instance if you total 4 Speed EVs you'll get 1 point in speed, 8 would yield 2, and 64 would yield 8. EVs max out at 255 for a single stat and 510 for total EVs, so it is often preferred to max out two stats with 252 (since the additional three don't give an additional point) and 4 in another and 2 EVs for some elbow room. In addition to fighting there are certain items you can collect that will give EVs. There are vitamins like Carbos and HP UP which will give the pokemon 10 EVs in that stat, but they stop working once you reach 100 EVs for that stat (so basically 10 per stat). As of Black and White there are also other items, feathers, that will give 1 EV to a specific stat. (Unlike Vitamins they don't cap at 100 and instead obey normal EV restrictions.)
DVs are essentially anything that separates one pokemon from another. These include Gender, Nature, Level, EVs, and IVs.
I recommend looking at Serebii's Game Mechanics section for more information.
http://serebii.net/games/mechanics.shtml -Serebii's Game Mechanics section
http://serebii.net/pokedex-bw/ -Serebii's Pokedex (click the dark gray buttons for EVs)