The 13th Amendment to the Constitution of the United States of America is straightforward:
The meaning is clear. The amendment outlaws slavery. It was passed by the Congress and sent to the states on 31 January 1865 and ratified by a sufficient number of states that it took effect on 6 December 1865.
The last state to ratify this amendment was Mississippi whose state legislature finally found the political courage to agree that slavery really should be illegal on 16 March 1995.