Alex Bargmann, Studied U.S. History in Undergrad
The Bill of Rights enumerates specific personal liberties that the national government, including Congress, cannot infringe on as well as limiting the federal governments in judicial procedures. This includes things like freedom of speech or the right to a trial by an impartial jury. Perhaps most importantly, instead of limit the rights reserved to the States and people by a list that the founders realized could be short sighted, the tenth Amendment reserves all powers not delegated to the federal government by the Constitution to the States and the people.
This is a very brief overview, I'd suggest watching this video or finding other resources on Noodle.