Federalism is like a 3-layer cake. The top layer is the Federal Government. This layer is like the frosting - it's the part that everyone can see and that binds the whole cake together. The Federal Government makes laws that apply to everyone in the country, like rules about taxes, money and civil rights.
The middle layer is the State Government. This layer is like the cake part - underneath the frosting, but still important. The State Governments make laws that apply just to the state they represent, like rules about driving, marriage, laws about schools and laws about healthcare.
The bottom layer is the Local Government. This layer is like the fruit or nuts in the cake - the parts you don't always see but it still adds a little something extra. The Local Governments make laws that only apply to the particular city or county that they serve, like rules about public safety, garbage pick up, parks and libraries.
Federalism is the sharing of power between the three layers, with each layer having its own roles and responsibilities. This creates an environment where everyone can come together, share ideas and work together to create laws that make the country better for everyone.