Varieties of Grape
The best way to understand about wine and its flavours is learn about grape variety. Each different grape varietal has its own hallmark flavours; so two wines made with the same variety produced in vineyards thousands of miles apart will have similar (although not identical) flavour characteristics. For example, wines made from the Sauvignon Blanc grape have aromas and flavours of grass, nettles and gooseberries. However wines from the Loire Valley tend to be less lean and green than New Zealand versions.
Not all wines are made from a single grape variety. Red Bordeaux, for example, usually contains at least three. However, once you know the taste of different grapes you should know what to expect from a blend.