It means that 12% of the volume of the wine is alcohol... imagine 100 tic tacs and pretend that each one was a piece of water. In your bottle of chardonnay, 12 of those 100 tic tacs would be alcohol instead of water. If you bought a bottle of vodka or tequila, those are 20% alcohol by volume, so 20 tic tacs of alcohol. Most beer is around 5%. Your level of "drunkeness" would depend on how well your body tolerates alcohol, your height/weight, whether or not you've eaten and how fast you drink it. Anyone who drinks an entire bottle of wine in 15 minutes will surely feel the affects. However, drink it over 4 hours while you've having several courses of dinner and the affects will be not be nearly as severe.