Okay, kiddo, so libertarianism is a type of political belief that says people should be free to make their own choices and live their lives however they want, as long as they don't hurt anybody else.
In the United States, libertarians believe that the government should stay out of people's personal lives and only do things that are absolutely necessary, like protecting people from harm or enforcing contracts between citizens. They also believe in free markets, which means that businesses should be allowed to compete with each other without the government controlling or regulating them too much.
Libertarians don't think the government should be spending a lot of money on things like social welfare programs or public education, because they believe those things should be left up to individuals and private organizations to figure out. They also tend to be against things like taxes and government regulations, because they believe that those things limit people's freedom and hurt the economy.
Basically, libertarians want people to have as much freedom as possible, and they think that the government should only be involved in things that are absolutely necessary to keep society running smoothly. Is that easy enough to understand?