Answer:
They are describing the idea that government is based on the consent of the governed, which is the foundational political idea of the US.
Step-by-step explanation:
The Declaration of Independence is a document drafted by the Founding Fathers of the United States. In the document they not only just wrote about their grievances against the British but also wrote about an idea form of government.
By stating "that to secure these blessings governments are instituted among men deriving their just powers from the consent of the governed," they were describing the idea that the government is based on the consent of the governed, which later became the foundational political idea of the US.