What is the role of each branch of government in the process of the federal government creates the laws that govern the entire nation

The legislative branch actually creates and votes on the laws. They also have the right to override any veto the president makes. So if the president vetoes a law that the legislative government makes, the legislative branch can override the veto with a simple majority

The executive branch actually enforces these laws and can pass executive orders which can override congress' ruling in an emergency

the judicial branch has the power to determine whether or not these laws are constitutional