The Atlantic slave trade had considerable impacts on both the Americas and Africa. Some of these impacts were felt in the short term while others were more long-term. The long-term effects can be said to stretch as far as Europe.
Of course, Africa was badly damaged by the slave trade. It was African people, mostly in the prime of life, who were taken away as slaves. This, of course, devastated the societies from which they were taken.
The Americas were, at least at first, helped by the slave trade. This trade did a tremendous amount to build the colonial economies. The independent United States was also helped by slavery as it grew to be more wealthy in the early 1800s. However, in the longer term, there were negative impacts on the United States and other countries of the New World. In the US, slavery helped to cause the Civil War. It has also, in the US and other countries, helped to create societies that have serious racial tensions.
Europe was impacted in much the same way as the Americas, but to a lesser degree. Slave labor in the Americas helped to enrich the European colonial powers. Later, migrations of people of African descent from colonies and ex-colonies to Europe has also helped to cause racial tensions in those societies.
Thus, the Atlantic slave trade has had short-term and long-term effects on many parts of the world.