Dear Sri KRS,
In this context, it means 'all that is manifest', while Prakrithi here means 'all that is unmanifest'.
I was under the impression that 'Purusha' is Soul and 'Prakrithi' is Nature. By implication Purusha is that which is more unmanifest in lesser evolved souls and Prakrithi is that which is more manifest.
Regarding your second question on 'what Isa says about how to get to the ultimate point' - the whole Upanishad is quoted above (only 18 verses). But there are various interpretations of the meaning of the verses and in my mind, the 'two fold' ways are indicated here. First with 'renunciation' and doing one's Dharma and the next by Samkhya, knowing both Avidya and Vidya.
So what are the intervening steps to this 'renunciation' and 'samkhya'. How does one do it?
Dear Sowbhagyavathi Chintana Ji,
I have given here the translation by Swami Nikhilananda Ji of the Paramahamsa Ramakrishna order. While the translation, in my opinion is true to the meaning of the slokha (I have read several other translations as well), I wish I know enough of Sanskrit to fathom the meaning of this slokha myself. So, within this context, I am answering your two questions above.
1. 'Unmanifested Prakrithi' is translated as 'unreal' and the 'Manifested Hiranyagarbha' is translated as 'real' in T.M.P. Mahadevan's translation and yet as 'non-becoming' and 'becoming' in others, in this context. One has to remember that this Upanishad is from the point of view of a person who just left his/her mortal coil. In my simple mind these translate in to, what is imagined and what is perceived. Just my own interpretation.
2. 'Renunciation' in my mind is synonymous with 'non-attachment', while 'Samkhya' is the acquisition of the discriminatory knowledge.
Interim steps? - I would hazard a guess - do your prescribed duty and offer it as a prasad to Him and meditate.