What is the "Supremacy Clause" and how does it affect State's powers to make

and enforce laws?

Supremacy clause is an essential clause for the Congress.

Explanation:

Supremacy clause allows any laws made by Congress to be supreme than the States or local government laws. Any law made by state cannot violate the law made by federal government. Also, states cannot regulate or interfere in any of the federal laws. This way Congress/national government is made powerful and supreme. This way states would always remain under the boundaries of the Constitution.

But this doesn't mean that federal government could review state laws before coming into effect.