अहमात्मा गुडाकेश सर्वभूताशयस्थितः। अहमादिश्च मध्यं च भूतानामन्त एव च ॥

aham ātmā guḍākeśha sarva-bhūtāśhaya-sthitaḥ aham ādiśh cha madhyaṁ cha bhūtānām anta eva cha

I, O Gudakesha, am the Self, seated in the heart of all beings; I am the beginning, the middle, and also the end of all beings.

In plain words: Krishna tells Arjuna, called Gudakesha, that He is the Self living in the heart of every being. He is the beginning, the middle, and the end of all living things.