The federal government is organized into three different branches including:
1) The executive branch (aka the president)
2) The legislative branch (aka Congress)
3) The judicial branch (aka the Supreme Court).
This form of government was created to ensure that no one individual had too much power. One of the most significant reasons why America became independent in the first place was due to a corrupt British government in which colonists believed King George III had too much power and did not consider the needs of the citizens. This is why the founders created a system in which the citizens elect members of the legislative and executive branch.
Along with this, the framers also created a system of checks and balances. This ensures that no one part of the federal government has too much power. Each branch has significant power but can be overruled by another branch. For example, if a President makes an Executive Order, the Supreme Court can declare it unconstitutional (aka illegal) if it is brought up in a court case. This makes sure that the President abides by the constitution.