This is a complicated issue and the causes and effects are multiple. Politicians and scholars have been trying to address the problem for many years.
First, let's look at some causes. One cause for the single-parent black family is historical. In the days of slavery, slaveholders had no interest in promoting the welfare of the black family, and routinely separated couples and/or their children from one another. Once the Civil War was over and slavery was illegal, families were not able to magically get back together. The history of not being permitted to remain in stable family relationships created a kind of "culture" of single parenting. People just did the best they could on their own. Another cause for single-parent frequency is the devastating circumstances in which black males have found themselves. They have a high incidence of incarceration and death, poor employment prospects, and low achievement in education. This makes many females feel they are poor prospects for marriage. Of course, some of these circumstances stem from continuing racism in the United States. Once there is a systemic culture of single parenting, there are fewer "happy two-parent" models for young people to follow, so the system tends to perpetuate itself. Still another reason for the high incidence of single parenting is the high rate of teen pregnancy among black youth. A teenage mother is probably going to be discouraged from marrying the father of her child for several reasons, one being that she should not be stuck with someone whom she doesn't necessarily want to be with for life, and another being that she should pursue her education before she marries.
What are the effects of the single-parent household on children? All the statistics show that children from single-parent households will not do as well as those from two-parent families. These children have difficulty in school, are more likely to use drugs and alcohol, to join gangs, to commit crimes, and to be teen parents. They are more likely to experience failure in the workplace and less likely to marry. This sounds rather bleak, I know, but there are many people from single-parent households who beat the odds and have happy, successful lives.
Good luck to you.