"Kṛṣṇa-mayī" means "one whose within and without are Lord Kṛṣṇa." She sees Lord Kṛṣṇa wherever She casts Her glance.
Or "kṛṣṇa-mayī" means that She is identical with Lord Kṛṣṇa, for She embodies the mellows of love. The energy of Lord Kṛṣṇa is identical with Him.
Kṛṣṇa-mayī has two different imports. First, a person who always thinks of Kṛṣṇa both within and without and who always remembers only Kṛṣṇa, wherever he goes or whatever he sees, is called kṛṣṇa-mayī. Also, since Kṛṣṇa's personality is full of love, His loving potency, Rādhārāṇī, being nondifferent from Him, is called kṛṣṇa-mayī.