IANAL, but the way I understand it is something like: You are a court, and you're trying to determine how the 5th amendment applies in some tricky case. The text itself might be ambiguous or unspecific in your case.

One way to approach that ambiguity is to look at the history of the amendment - why was it written, and given that, what is the most likely intended way to read it?

For the 5th amendment, the context is that the Court of Star Chamber used the inquisitive method, combining the search for truth with the force a court is able to apply to a defendant. In doing so, the Court of Star Chamber highlighted a flaw in the inquisitive method: Combining the right to apply force to its subjects with the job of determining truth created incentive for extensive abuse, as the court forced false testimonies out of its subjects.

Hence, the 5th amendments no-self-incrimination clause can be interpreted to exist to weaken the inquisitorial method in US courts, reinforcing the US commitment to an adversarial system instead.