Of the Vedas I am the Sâma-Veda; I am Vâsava of the Shining Ones; and of the senses I am the mind; I am of living beings the intelligence.
In plain words: Krishna says that among the holy books called Vedas, He is the Sama Veda, the book of sacred songs. Among the gods, He is Indra (Vasava). Among the senses, He is the mind. In living beings, He is the power of awareness and intelligence.