Answer:
During cytokinesis, which is a physical process of cell division, the cells divide the cytoplasm of a parent cell into two daughter cells. The ring on the outside of the cell which is also known as a contractile ring, shrinks at the equator of the cell which causes pinching, and the plasma membrane goes inward. After all that happens there’s something called a cleavage furrow which is the formation of a dip between the two cells while they are splitting.
(You can sum it up, but I hope this helps!)