The "Mockingjay" epilogue takes place at least 20 years after the main Hunger Games story arc, and it explains Katniss and Peeta's lives as adults. They live peacefully with their two children after the yearly Hunger Games are abolished.
In the epilogue, Katniss reflects on her life and wonders how she could explain the Hunger Games to her children. She says that she never wanted kids, but Peeta wore her down after 15 years. Katniss realizes that she must eventually explain her role in Panem's history to her children, but she has no desire to revisit those dark times. "Mockingjay" ends sadly, as Katniss does not seem to enjoy her family or her quiet life.