Many Bordeaux wines do not contain all of these grapes, but most of them are blends of at least some of these (and a very few may be limited to just one of these varieties):
Cabernet sauvignon ("cab-air-nay so-veen-yawn"): Has a profile of black currants, black cherry, plums, spices, vanilla. A purple wine. An ideal variety for aging. But it needs blends, for softness and complexity. I have learned to be leery of many 100% cabs. Medium-to-full bodied. Late-ripening; it needs pretty extreme heat units. The palates of the people of the world have decreed that this is the King of Grapes. I actually do not agree. But you cannot dispute its importance.
Cabernet franc (pictured): A parent (along with Sauvignon blanc) of Cabernet sauvignon. Profile: pepper, tobacco, plum, and sometimes violets on the nose, and plum, raspberry, currant on the palate. Lighter body; fruitier and more herbal than Cab sauv. It makes a bright red wine. Cheval Blanc, a famous St. Emilion chateau, is primarily Cab franc.
Merlot: Named for the Old French word for "blackbird" (for the grape's black color and the love those birds have for this grape). Medium-bodied; softer. A great "entry grape" for those learning about red wine. Profile: Berry, plum, currant, black cherry. A sibling of Cab sauv. Chateau Petrus (the worlds most expensive wine, after DRC?) is 90% Merlot. Don't believe what you see in movies; this is a GREAT grape.
Petit verdot ("puh-tee vair-doh"): Ripens very late; is no longer very successful in Bordeaux. Adds tannin, color, and leather notes. Bouquet is dark fruits, violets, and leather. Palate has vanilla, smoke, spice, cedar, molasses, and dense, dark fruits. It is obscure, having as parents Tressot and Duras. Is growing well in Washington.
Malbec: Inky dark. Strong tannins. Medium-to-full body. Plums, blackberry, violets and tobacco. Very jammy, due to its rich fruit and unctuousness. Interesting: Try it with Mexican, Cajun, Indian, Italian, and barbecue! Not much grown in Bordeaux, but has become the signature grape of Argentina and is enjoying a rapid (well-deserved) rise in popularity.