Krsna has many types of potencies, parasya saktir vividhaiva sruyate svabhav… , because He has to execute so many affairs, this material world, spiritual world, and just imagine so big universe. There are innumerable universes, and in each and every universe there are so many planets, so many different kinds of living entities, and He has to manage everything.
Therefore He is called Paramesvara. Paramesvara means the supreme controller. And Krsna says in the Bhagavad-gita, sarvasya caham hrdi sannivistah [Bg. 15.15]: "I am living in everyone's heart." Now, imagine. There are innumerable universes, and each and every universe, there are innumerable planets, and in each and every planet, there are innumerable towns and cities, and each and every town, there are innumerable living entities, and Krsna has to manage all of them. That is Krsna.
From Srila Prabhupada's lecture on Srimad-Bhagavatam 1.7.6 — Vrndavana, April 18, 1975