Nirtha Manasa Sangyama means dharana dhyana samadhi. Meditating in this way, shantim nirvana parama, mudsangsthaam adhigatchati. In Vedanta and in Buddhism, it is used to mean the extinction of samsara. One meaning is to meditate upon Brahman, upon your inner self.
Swami Sarvapriyananda teaches Chapter 6 (Verse 15) of the Bhagavad Gita. In this series of talks, Swami Sarvapriyananda unfolds the highest truths of Vedanta through the study of the Bhagavad Gita (The Song of God).