Synonyms:

tasmat–therefore; tvam–you; indriyani–senses; adau–in the beginning; niyamya–by regulating; bharata-rsabha–O chief amongst the descendants of Bharata; papmanam–the great symbol of sin; prajahi–curb; hi–certainly; enam–this; jnana–knowledge; vijnana–scientific knowledge of the pure soul; nasanam–the destroyer.

Translation:

Therefore, O Arjuna, best of the Bharatas, in the very beginning curb this great symbol of sin [lust] by regulating the senses, and slay this destroyer of knowledge and self-realization.