The Descendants tab displays information about the descendants of the focus person. Each descendant is shown in a box on a line of their own. You can expand branches to explore further.
The spouses of each descendant are shown on the same line as the descendant, to the right of the descendant box. Where there is any ambiguity about which spouse goes with which offspring, the line connecting the child is marked with the given name of the spouse in question. You can configure the display in the Focus Window tab of Preferences.