In the 12^th chapter makes the end of madhyama śatakam of Bhagavat Gita.  Each śatakam consists of six chapters.  The three śatakam and the topics highlighted are:

Prathama śatakam:  First part of Gita (First to 6^th Chapter); Topics:

1. Jiva swaroopam,
2. Karma yoga,
3. Importance of individual effort or prayarthana.  Everything is not pre-determined; we also have free will. Fate alone does not determine our future and we should not embrace fatalism.  Vedic approach is fate is only one of the contributors to our future.  In addition to fate, the other important factor is our free will or purusärtha or parayarthana.  Only when you work for your own upliftment, God will come to your help.

Madhyama śatakam:  Seventh to 12^th Chapter Topics:

1. Eeswara swaroopam. 
2. Eeswara upasana yoga.  Meditation up on eeswara.  This can be in the form of ishta devata upasanam or in the form of viśvarũpa upasanam, meditating up on the lord as the very universe itself. 
3. Importance of Eeswara anugraha or the help from the Lord.  Even the greatest advaidin should value the role of eeswara anugraha. 

Charama śatakam (13^th to 18^th)

1. Eeswara jiva swaroopa aikyam.  The essential oneness of eeswara swaroopam and jiva swaroopam. We indirectly convey there is superficial difference between jiva and eeswara, similar to wave and ocean.  The difference between the two (like size, length of time etc..) are only superficial.  The essential nature of ocean and wave is water.  There are no waves without water and there is no ocean without water.  If you shift your focus to water, then waves and ocean are essentially one and the same.  Similarly, jivatma is essentially atma; paramatma is essentially also atma. 
2. jñāna Yoga as a sadhana, meant to discover the essential oneness.  Once the wave discovers that it is water, then there is no end for the wave.  jñāna yoga is understanding the equation that jivatma equals paramatma.  When you look it eeswara and when you look at jiva, they are very different.  paramatma is omniscient, omnipotent, omnipresence.  Jivatma is exactly the opposite of this.  But the differences are only superficial.  When you arrive at the essence of jivatma and paramatma, you discover that they are essentially one and the same.  The inquiry you make to arrive at this conclusion is jñāna yoga or vedanta sravana, manana nidhithyasanam.
3. Importance of values; developing sat guna, noble virtues.  Just like we prepare the ground, before sowing the seeds, we should develop noble virtues to understand vedanta; these values are also known as sadhana catuṣṭaya saṃpatti.

Verse 1:

Arjuna asked – Oh Lord! I desire to know the following: prakriti, purusha, kṣetram, kṣetrajña, jñānam and jñeyam.

Arjuna gives six technical words of vedanta and asks for clarification.  The words are:

1. Prakriti
2. Purusha,
3. kṣetram,
4. kṣetrajña  
5. jñeyam.
6. jñānam

Some of these words are synonymous.  The words prakriti and kṣetram, are synonymous, both of them are products of material world and are the objects of our experience.  According to vedanta, it includes the world, energy, body, and mind.

Purusha, kṣetram and jñeyam are all synonymous, they all stand for chaithanyam or consciousness. 

jñānam is the only word left out.  In this chapter, jñānam means virtues or values or sat guna.

So, the six technical words are condensed into three concepts:

1. Prakriti and kṣetram. These two words stand for material aspects.
2. Purusha, kṣetram and jñeyam; they all stand for consciousness.
3. Jñānam, meaning sat guna in this context.

Verse 2

Lord Krishan said Oh Arjuna! This body is known as kṣetra (There is a conscious principle) which knows this (body).  Wise men declare that knower principle to be kṣetrajña.

Krishna rearranges the questions, Krishna starts with the third item, kṣetram.  This body you are experiences is kṣetram.  Meanings of kṣetra as told by Sankarachariyar:

• One that is subject to decay; disintegrates and dies.  The word śarīram also means the same thing.  The word śarīram or dehaha refers to suffering from threefold factors:
  • Internal, (body getting old, getting decease, etc.).
  • External.
  • Nature or dharma 
• Any agricultural field is called kṣetram and our physical body is comparable to a field.  Just like the seeds grow at different times, our karma also fructifies at different times.  Just like seeds require land to grow into plants, we require body to convert pavam into suffering and punyam into sugam.  We also should include the mind and external world as kṣetram.  Body, mind, and external world are all called kṣetram; whatever you experience is kṣetram.  All the three are objects of experience and made up of matter.  All the three are subject to constant change.  World, body, and mind are all subject to change and savikaram.  Krishna focusses on the body because we are focused mostly on body. 

The second topic is whatever illumines the kṣetram.  An experience presupposes a sentient experiencer or perceiver or conscious principle and that is called kṣetrajña.   In short, kṣetrajña means consciousness principle.  kṣetram means material principle.

What is the nature of this consciousness is a fundamental question.  According to vedanta, consciousness has the following principles:

1. It is not a part, product, or property of the body. 
2. It is an independent entity that pervades the inert body and makes it sentient.
3. It is not limited by the boundaries of the body; it extends beyond the periphery of the body.
4. It will continue to exist even after the body perishes; it is eternal.
5. The surviving consciousness is not recognizable because there is no body for it to manifest or express.