sa saptabhih satair eko
vimsatya ca satam samah
gandharvair yuyudhe bali
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The five-hooded serpent, the superintendent and protector of the city of King Purañjana, fought with the Gandharvas for one hundred years. He fought alone, with all of them, although they numbered 720.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The 360 days and 360 nights combine to become the 720 soldiers of Candavega (time). One has to fight these soldiers throughout one’s life span, beginning with birth and ending with death. This fight is called the struggle for existence. Despite this struggle, however, the living entity does not die. As confirmed in Bhagavad-gita (2.20), the living entity is eternal:
na jayate mriyate va kadacin
nayam bhutva bhavita va na bhuyah
ajo nityah sasvato ’yam purano
na hanyate hanyamane sarire
“For the soul there is never birth nor death. Nor, having once been, does he ever cease to be. He is unborn, eternal, ever-existing, undying and primeval. He is not slain when the body is slain.” Actually the living entity does not take birth nor does he die, but he has to fight with the stringent laws of material nature throughout the entire span of his lifetime. He must also face different kinds of miserable conditions. Despite all this, the living entity, due to illusion, thinks that he is well situated in sense gratification.