Lord Krishna explains the nature of the eternal soul and the concept of Brahman, the ultimate, imperishable reality. He discusses the significance of thoughts at the time of death, emphasizing that whatever one contemplates in their final moments will shape their next existence. Krishna teaches Arjuna about the process of attaining liberation by focusing on the divine and practicing unwavering devotion. He describes the paths of light and darkness, or the cycles of rebirth and liberation, and explains that those who attain him are free from the cycle of birth and death, reaching an eternal union with the divine.