The Tenth Amendment is intended to make sure that the states would have a fair amount of power under the federal system that the Constitution created.
The Tenth Amendment says that the states or the people hold all rights unless those rights are specifically given to the national government by the Constitution or those rights are specifically taken away from the states. For example, the Constitution specifically says that the states may not make treaties with foreign governments. Therefore, this power is not given to the states. However, the Constitution does not give police powers to the federal government. Therefore, under the 10th Amendment, the states have these police powers.
The point of this amendment is to make sure that the states retain power. It is meant to say that in cases where the Constitution is not clear, it is the states that get the power, not the federal government.