The 1st house (Lagan) represents the physical body, the mind, and the core character of a person. Saturn (Shani) is the planet of darkness, secrecy, and strict Karma.
When Saturn sits in the 1st house, it literally "wraps its arms" around the person's mind. If this Saturn is negative or afflicted, Dr. Sharma warns that the person will naturally gravitate toward dark, unethical, or illegal activities ("kartooten kaali hongi"). They will become highly secretive, manipulative, and willing to harm others for their own gain.
However, Saturn is the Lord of Justice. If they do not correct their character, Saturn will eventually punish them with severe health issues and public humiliation.