Federalism, as we know, is the United States system of government, It's designed to balance the authority of the national government and state governments. How does it affect lawmaking process and enforcing laws then?
Well, there's this system called Checks and Balances.
Checks and Balances is the system in which the government is divided into three branches. The Legislative, Executive and Judicial branch. Each branch has its certain power, with certain power over the other branches (If that makes sense). This is done so that all three branches are equal, or balanced. Also to prevent a branch from gaining too much power.
So let's say that congress wants a new law to be added, the procedure of the bill becoming into a law is a complicated process. First, the bill must pass both houses of congress with a majority vote (agreeing to the bill). After it passes congress, it's sent to the Executive branch, or the president. If the president agrees and signs the bill, then the bill will become a law. But, if the president doesn't sign the bill, it means the it's been vetoed, or rejected. And the bill goes back into congress, and this time if bill gets a two- thirds majority vote, then the bill becomes a law even without the president's signature.
As you can see it's a really complicated process. But, it makes sure that no branch can overpower another branch and everything remains balanced.