prakritim yanti mamikam
kalpa-ksaye punas tani
kalpadau visrjamy aham
"O son of Kunti, at the end of the millennium all material manifestations enter into My nature, and at the beginning of another millennium, by My potency, I create them again."
Here He says that with His will power [sankalpa shakti] He creates, destroys and after lord Brahma's life time, all the worlds are all dissolved and again creates when lord Brahma's lifetime begins. He does not move any limb to do all , but everything is done by this will power. In the previous sloka He said He is supporting all by His will power. Here, He says besides support, pervading and commanding, He creates, sustains and destroys and all are dependent on Him. He addresses Arjuna as His aunt Kunti's son, so that he would listen to Him. Sarva bhutani = all living beings and objects, kalpa = Brahma's life time, ksaye =when ends. So we should note that there is end to Brahma also and only the Lord is endless. Other than Vaikuntam, all other Universe and all living and non-living objects are created on a particular time and destroyed at another time. So all atman, be of a tiny grass or Brahma or devas or animals or birds, get dissolved at the end of Brahma's lifetime. Mamikam = in My [Sri Krishna's] body, yanti = attain. That is all these atman and other matters, at the end of Brahma's life time get dissolved and merge into the Lord's body or moola prakruti. Kalpadau = again when Brahma's life time starts, puna = again, stani = all these [atman and other matter mingled in moola prakruti], visrujami = get created by, aham = Me [Sri Krishna]. So both creation and destruction are all His deeds. In Vishnu puranam, sage Parasara says that all creations, sustainment and destruction are all done by the Lord by mere thinking or will power. In Brahadaranya Upanishad there is an important portion Gargi prasnam. The sage preaches Gargi. that Sun or Moon are all supported by the Lord by His will power. Initially, He decides to create the Universe. Similarly, He decides to dissolve the Universe. So, His will power decides creation, support and destroying. Layam or dissolution is talked here. Pralayam or end, is in many categories. Every living being dies and this is called Nitya pralayam or daily occurance. It affects individuals. We have seen that Brahma has one day equal to 1000 chatur yug or 1000 X 4,320, 000 [our, human] years. At the end of Brahma's one day time, the three worlds bhu, bhuva and suva are dissolved [upper worlds like maha, jana, tapa and satya lok or worlds are not affected]. This is naimittika pralayam or occasional. This lasts till the night time of Brahma [ another 1000 X 4,320,000 years] is over. There after, again these three worlds -bhu, bhuva and suva- get created. When the Life of Brahma ends - that is after 100 Brahma years of 365 Brahma days [ equal to 2 X 1000 X 4,320,000 human years], there is yet another pralayam. That pralayam is what Sri Krishna mentions in this sloka. At that time all the worlds, including that of Brahma -satya lok- are dissolved and merge into the body of the Lord, which is moola prakruti. We have seen in Chapter 7, how this Universe and all are created from moola prakruti. [Moola] prakruti---> mahan--> ahankaram--> Pancha bhoothani--> Pancha tanmatra--> Pancha karmendriya --> pancha gyanendriya--> manas. All these emerge from the body of the Lord during creation. In pralayam all get dissolved and there is no form or name. All will be in subtle form as contrasted from our present gross form. This happens at the end of lifetime of Brahma. Again when Brahma's life time begins, creation of all, starting from satya lok is effected. Every living being gets a body craeted. All creations and destructions are carried out by the Lord out of His will power alone. This pralayam is called prakruta pralayam. There is yet another pralayam, the Fourth one is called, Adyantika pralayam. This is when an individual soul reaches Moksham.