कर्मणः सुकृतस्याहुः सात्त्विकं निर्मलं फलम्। रजसस्तु फलं दुःखमज्ञानं तमसः फलम् ॥

karmaṇaḥ sukṛitasyāhuḥ sāttvikaṁ nirmalaṁ phalam rajasas tu phalaṁ duḥkham ajñānaṁ tamasaḥ phalam

It is said the fruit of a good action is harmonious and spotless; verily the fruit of Motion is pain, and the fruit of Inertia unwisdom

In plain words: Krishna says good action brings pure, peaceful results. Passion brings pain, and dullness brings ignorance.