Complex sentence: She is the elder daughter of Nelson Mandela and his (second) former wife, Winnie Mandela, she was aged 4 when Nelson was sent to prison, and she was not able to visit her imprisoned father until 1974, when she was 16 years old.
Split into simpler sentences: She is the elder daughter of Nelson Mandela and his (second) former wife, Winnie Mandela. She was aged 4 when her father was sent to prison, and she was not able to visit him in prisoner until 1974, when she was 16 years old.