Okay, so a long time ago in the United States, there were people called Native Americans who lived there before anyone else. But then, some other people from Europe came and decided that they wanted to take over the land where the Native Americans lived. They started to take the land away from them and make them work for them.
Sometimes, the Europeans would capture Native Americans and make them work without paying them or treating them fairly. This was called slavery. Other times, the Native Americans would get in trouble with the law and be sent to jail. But the jails were usually really crowded and not very nice places to live.
So, in order to help the Native Americans who were enslaved or in jail, the US government made a law called the Act for the Relief of Indian Slaves and Prisoners. This law said that the Native Americans who were enslaved by Europeans should be given their freedom and treated fairly. It also said that the Native Americans who were in jail should be given better living conditions and treated more fairly as well.
Basically, this law was trying to make things better for the Native Americans who were being mistreated by the Europeans. It was a way for the US government to say "Hey, it's not okay to treat people like this," and try to make things right.