avatārera - of the incarnation; āra - another; eka - one; āche - there is; mukhya-bīja - principal seed; rasika-śekhara - the foremost enjoyer of the mellows of love; kṛṣṇera - of Lord Kṛṣṇa; sei - that; kārya - business; nija - own.

There is a principal cause for Lord Kṛṣṇa’s appearance. It grows from His own engagements as the foremost enjoyer of loving exchanges.