। ॥ २६४ ॥
In plain words
It shines entirely on its own, with nothing else beside it — supreme beyond even the supreme. One single essence, known from within, and that essence is exactly what you call your Self. Being, awareness, joy — infinite, undying. That is Brahman. And that is you. Hold it within.
Close to the Sanskrit
That which shines, without anything else [beside it], supreme beyond the supreme; of a single inward essence, characterized as the Self; existence-consciousness-bliss, infinite, imperishable — that Brahman [is]: thou art That; contemplate [this] within yourself.