The verse expresses Lord Krishna's promise to appear whenever righteousness declines to protect the good, destroy evil, and restore dharma, often used in meditation and prayer.
You can find the full lyrics for the popular Bhagavad Gita verse "Yada Yada Hi Dharmasya" (Chapter 4, Verses 7-8) from various online sources, including: YouTube (Various chanting videos) Bhagavad Gita Online (Text and meaning) yada yada hi dharmasya lyrics download