Separation of powers is just what it sounds like. It separates the different groups (branches) of the US government. It is separated into three branches; the Legislative, executive, and Judicial. Each group is in charge of a different part of the US government. They are seperated to keep one group from having too much power over the nation.
Legislative- These people are in charge of making laws and are composed of the House of Representatives and the Senate, which forms congress.
Executive- This branch consists of the President and Vice President and they are in control of enforcing the laws that this country sets in place.
Judicial- They are composed of the supreme court and they decide on how the laws are interpreted. They also decide on punishments for those who break the laws.