This is not a mantra. It is a prayer by a great saint who is glorifying the Supreme Lord Sri Krishna, his names, pastimes, qualities and so on. Sri Hari was a monk in Hare Krishna movement until he passed away a few years back. The movement concentrates on letting people experience spiritual bliss by continuous chanting and listening of the Hare Krishna Maha Mantra:
Hare Krishna Hare Krishna Krishna Krishna Hare Hare
Hare Rama Hare Rama Rama Rama Hare Hare
and also from which I have benefitted greatly practising at home, and you can too!! Its great!
Lyrics of Vande Krishna:
Steps to Maha Mantra Meditation: