What does martin luther king mean by justice-equality of rights , equality before the law , equality of opportunity, equality of economic and social condition, or something else ?

Based on the article posted on January 14, 2017 by Andrea Estrada on the web page named "The Current" Martin Luther King had a dream and it was the dream of equality and justice for the African-American.

What he means by saying  "equality before the law , equality of opportunity, equality of economic and social condition, or something else" That speech, and his exhortation for a society that would judge his children not “by the color of their skin, but by the content of their character,” has become the most common representation of King as a symbol of the fight for racial equality.