Imagine there is a disagreement about what a new law means. Which branch of government would help explain the law?

The judicial branch would explain the law.

The President leads which branch of government, and what is that branch responsible for?

The President leads the executive branch, which is responsible for carrying out the laws.

I can understand what the three branches of government do.

1
The three branches of the U.S. government are the legislative, executive, and judicial.
2
The legislative branch makes laws, the executive branch carries out the laws, and the judicial branch interprets the laws.
3
Each branch of government can check on the others to make sure everyone is playing fair; this is called checks and balances.