Lamech said the same thing twice for emphasis. His voice is a synecdoche for his whole person. AT: "listen carefully to me" (See: [[rc://en/ta/man/translate/figs-parallelism]] and [[rc://en/ta/man/translate/figs-synecdoche]])
Lamech killed only one person. These two phrases means the same thing and are repeated to emphasize the certainly of his action. AT: "a young man because he hurt me" (See: [[rc://en/ta/man/translate/figs-parallelism]])
Lamech knows that God will avenge Cain seven times. AT: "Since God will punish anyone who kills Cain seven times, Lamech" (See: [[rc://en/ta/man/translate/figs-activepassive]])