Definition - What does Yama mean?
Yama is the Sanskrit name of an Asian god who is mentioned in the yogic texts of the Vedas. His name means “twin” and, in Hindu mythology, he sometimes appears with his twin sister, Yami. In the Vedas, he is said to be the first mortal who died. After his passing he became known as the "Lord of Death." In Hinduism, he acts as a guide for those who have died. Yama is thought to be the son of Surya, the sun god. He is also sometimes called Imra.
In Buddhist mythology, Yama is known as a dharmapala (wrathful god) or dharmaraja (dharma king).
Yogapedia explains Yama
Although Yama is considered by some to be a figure of terror, it is only in later mythology that he is associated with punishing the wicked for their bad deeds. In these cases he is portrayed as a god of justice as well as death.
In Hinduism, Yama has assistants who help him in his work. They are kala (time), jwara (fever), vyadhi (disease) and asuya (anger). He is described by some Sanskrit sources as being dark colored, with red clothes and seated on a buffalo or lion throne. Sometimes Yama is shown with four arms wearing golden yellow and holding a noose and stick.
In the "Rig Veda," Yama is a king who dwells in celestial light and lives in heaven. His kingdom is of bright homes for the pious and worthy of those who come to live with him. In the "Katha Upanishad," Yama teaches a little boy named Nachiketa about human nature, the soul and liberation.