In other words if powers aren't given to the government by the constitution the powers go to the states and people.
"The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people."
This gives rights to states and people to make their own decision. For example if the government wanted to build more schools in Tennessee they couldn't because they don't have the right to do so, that would be up to the states.
The Amendment was wrote to give limited powers to the federal government. Before the amendment was wrote the powers of the government and states were unequal.