What does this mean in simple terms?!?

Sounds like the sentence is referring to the 5th Amendment right not to incriminate yourself (say things that would allow you to be prosecuted). It says that so long as the government can try to force people to say things that might incriminate them (either in court or before a political body like Congress), the 5th Amendment right not to speak can be used as a defense. In other words, if the government did not try to force people to testify, then we might not need the 5th amendment, but because they do try, we do need it.