Answer:
It grants citizenship to "all people born or naturalized in the United States" which included former slaves who had just been freed after the Civil War.
The system of laws was called apartheid.
As the Civil War drew to a close the primary issue on the mind of the North was how to reintegrate the South back into the Union. They settled on the famous 10% plan for this. Regarding the fate of the ex-slaves, the North instituted Reconstruction, which sought to make sure that the freed blacks would be integrated into Society fairly. This largely failed, however.
