ete camsa-kalah pumsah
krsnas tu bhagavan svayam
mrdayanti yuge yuge
ete—all these; ca—and; amsa—plenary portions; kalah—portions of the plenary portions; pumsah—of the Supreme; krsnah—Lord Krsna; tu—but; bhagavan—the Personality of Godhead; svayam—in person; indra-ari—the enemies of Indra; vyakulam—disturbed; lokam—all the planets; mrdayanti—gives protection; yuge yuge—in different ages.
All of the above-mentioned incarnations are either plenary portions or portions of the plenary portions of the Lord, but Lord Sri Krsna is the original Personality of Godhead. All of them appear on planets whenever there is a disturbance created by the atheists. The Lord incarnates to protect the theists.
In this particular stanza Lord Sri Krsna, the Personality of Godhead, is distinguished from other incarnations. He is counted amongst the avataras (incarnations) because out of His causeless mercy the Lord descends from His transcendental abode. Avatara means "one who descends." All the incarnations of the Lord, including the Lord Himself, descend on the different planets of the material world as also in different species of life to fulfill particular missions. Sometimes He comes Himself, and sometimes His different plenary portions or parts of the plenary portions, or His differentiated portions directly or indirectly empowered by Him, descend on this material world to execute certain specific functions. Originally the Lord is full of all opulences, all prowess, all fames, all beauties, all knowledge and all renunciations. When they are partly manifested through the plenary portions or parts of the plenary portions, it should be noted that certain manifestations of His different powers are required for those particular functions. When in the room small electric bulbs are displayed, it does not mean that the electric powerhouse is limited by the small bulbs. The same powerhouse can supply power to operate large-scale industrial dynamos with greater volts. Similarly, the incarnations of the Lord display limited powers because so much power is needed at that particular time.