No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger; nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation.
The first part of the Fifth Amendment says that if you commit a capital crime, like espionage, you have to be tried by a Grand Jury. A Grand Jury doesn't try the criminal for his crime, but rather examines the evidence to decide if criminal charges should be brought. A Grand Jury usually consists of 12 jurors.
Double Jeopardy is more than just 2 Daily Doubles. In a Constitutional sense, it means that someone can't be charged with the same thing more than once. The second part of the Fifth Amendment says that no one should twice be put in jeopardy of life or limb.
The third part of the Fifth Amendment says that "nor shall be compelled in any criminal case to be a witness against himself." This means that you don't have to answer questions if a police officer asks and the question incriminates you. This has had some controversy. In the case of Ernesto Miranda, he had his fifth amendment rights violated and he was forced to testify against himself in his trial. The case went all the way to the Supreme Court, where he was declared innocent because he wasn't told his rights. Now, police officers have to read out the Miranda Rights when they make an arrest.