Answer: "Separate, but equal" meant that African Americans could not use vehicles or go to the same places as the white people, but they would be the same. This is important in the Plessy v. Ferguson case because Plessy was a one-eighth black man and when the conductor asked him if he was a black man, he said "Yes". Due to the fact that he claimed he was a black man, he was told to get off, but refused to do so. Even if he was one-eight black, it didn't matter to the conductor because Plessy was still somewhat black. Since Plessy was black, he was not technically allowed to ride on the "White Only" train because they were supposed to be segregated. The effect of Plessy's decision in the end was that segregation became law and it spread over America like wildfire.
