In the 19th century, before the civil war, they were not allowed to vote at all and had no suffrage rights. After the civil war, they got general suffrage according to the amendments made to the constitution. However, their suffrage was limited by local governments which introduced voting taxes without which you couldn't vote, or literacy tests which african-americans of the time could not pass. In the 20th century, african-american women got their voting rights when the 19th amendment was passed allowing women to vote. They got their full voting rights in the 20th century when things like limiting voting was banned.
A slave is a person that belongs to another one and is treated as property. Serfs, I'm not so sure about this now, were renting the land out from the landowners.
Ang pariralang ito ay nangangahulugang ang isang babae ay kasing laki din ng isang lalaki. Ang isang mahusay na babae ay nagdadala ng isang mahusay na tao. Nangangahulugan din na maraming kababaihan ang maaaring hindi nai-kredito para sa kanilang mahusay na pagsisikap at trabaho.