Answer:
To reconstruct is to repair something, to rebuild a damaged construction in order to help it stay as safe and healthy as always.
In America, the term Reconstruction has been used to refer to a period in American history that started after the end of Civil War in 1865, when the Confederacy was defeated and the South was under Northern control, both politically and economically. There were huge differences within society, mostly about slavery, but also other minor diferences.
Therefore, as we can see, the country was almost broken. Although the secession was stopped, there was a de facto division between north and south. As a consequence, the Federal Government started to made efforts in order to end these divisions and reunite both sides of society again. This process was called Reconstruction, and included policies such as recognizing African Americans the right to vote, among other measures.