Of brāhmaṇas, kṣatriyas, vaiśyas and śūdras, oh scorcher of enemies, actions are distributed according to the guṇas born of one’s own nature.

The four varṇas (social classes according to guṇa-karma). Parantapa — who torments enemies (Arjuna).

Karmāṇi pravibhaktāni — distributed actions, assigned. Svabhāva-prabhavaiḥ guṇaiḥ — according to guṇas born of one’s own nature. Not rigid hereditary caste but function according to psychic constitution.