The purpose of Marin Luther King Jr's speech was that for freedom and jobs for the colored folks.
When MLKJ delivered the speech, African Americans didn't have much freedom. He explained that if there was no racial justice between colored and white people, life wouldn't be peaceful. He also pointed out, even though the Emancipation Proclamation was already passed 100 years ago to free out slaves that colored people were not allowed in certain bathrooms, restaurants, and parks.