God Uses Me as a Spearman

Zhang Baixuan, who traveled to a strange world, came with a system called the "Swallowing System". However, this system is dead and cannot be used at all. For three years, Zhang Baixuan tried his best, but to no avail. But who would have thought that when he and his wife went to the secret realm to practice, the system inexplicably woke up! He also said something incomprehensible: [After sensing the system owner and killing the opponent, you can start to devour the system] What does this mean?