"Adah gave birth to Jabal; he was the father of those who live in tents and raise livestock. His brother's name was Jubal; he was the father of all who play the harp and flute. Zillah also had a son, Tubal-Cain, who forged all kinds of tools out of bronze and iron. Tubal-Cain's sister was Naamah." NIV translation
We are introduced to the seventh generation of people and remember that seven is the number of completion throughout the Bible. Because of the fall, men were required to work and, here, we see the start of various occupations such as shepherd, musician, and ironworker. Although we are not told of Naamah's occupation, her name suggests that she was a singer.