The significance of the Force Bill is that it overrode South Carolina's effort to nullify federal laws during the Nullification Crisis. It was the first law to explicitly deny that states had the right to secede as well.
During the Nullification Crisis, South Carolina claimed it had the right to ignore any federal laws that it thought were unconstitutional. By doing this, it was saying that the states had the right to determine what federal laws they would or would not obey. Pres. Andrew Jackson then pushed for the Force Bill. He believed that the Constitution would be worthless if states had the right to nullify laws and/or to secede.
This crisis was one of the first major incidents that worked to push the North and South apart.