Simplify the following text for a Grade 12 native English-speaking person.
Original: William Lloyd Garrison ( December 12 , 1805 â `` May 24 , 1879 ) was a prominent American abolitionist , journalist , and social reformer .
Simplified: William Lloyd Garrison ( December 13 , 1805 â `` May 24 , 1879 ) was an American abolitionist , meaning he wanted to end slavery in the United States .