It means that when the founding fathers created the U.S government they "split" it into 3 branches, The executive branch, The judicial branch, and the legislative branch. The executive branch consists of the president and vice president (and more); It is responsible for "Implementing and enforcing laws created by congress. The president posses the power to veto laws and in the event The president is assassinated the vice president is inaugurated as president. The judicial branch is responsible for interpreting U.S laws and the U.S constitution, and the legislative branch is responsible for making the laws, it is made up of The house of representatives and the senate.
If I missed anything or you require further "Questioning" Just make another question/
