Transliteration
sva-dharmam api caveksya na vikampitum arhasi
dharmyad dhi yuddhac chreyo 'nyat ksatriyasya na vidyate
Translation
Considering your specific duty as a ksatriya, you should know that there is no better engagement for you than fighting dharma and righteousness; and so there is no need for hesitation.
Purport
After explaining the secrets of soul and life, Bhagvan Shri Krishna reminded Arjuna of his natural duty. He is a kshatriyas and to fight to protect dharm, humanity and justice is his natural duty. It is a great honour for any Kshatriya to get such chance. Therefore he should not hesitate to perform his natural duty.
Bhagvan Shri Krishna further explained Arjuna that standing for the protection of Dharma and humanity is the prime duty of a Kshatriya(soldier). This not only protects the humanity but also opens the doors of heaven. Even if that kshatriya dies fighting he reaches to higher planets.