This tab is in the Sport Setup tab.
The Genders tab is used to define the names used for the different gender groups used in events. Your events may use "Men" and "Women", or you may use "Boys" and "Girls". Some events are open to participants of both sexes. You might call these events "Mixed", or you might call them "Open".
The ID field is the unique ID for this Gender. The default ID prefix is G.
The Name field is the name of the gender group.