ब्रह्मानन्दनिधिर्महाबलवताहङ्कारघोराहिनासंवेष्ट्यात्मनि रक्ष्यते गुणमयैश्चण्डैस्त्रिभिर्मस्तकैः ।विज्ञानाख्यमहासिना द्युतिमता विच्छिद्य शीर्षत्रयंनिर्मूल्याहिमिमं निधिं सुखकरं धीरोऽनुभोक्तुं क्षमः ॥ ३०३ ॥
In plain words
Deep within you lies a treasure - the very bliss of Brahman - but it is coiled about by an immensely powerful, terrifying serpent: the ego, with three fierce heads born of sattva, rajas and tamas. Take up the great, bright sword of discriminating knowledge, sever all three heads, tear the serpent out by its roots - and, as a steadfast knower, you can enjoy that treasure of pure joy.
Close to the Sanskrit
The treasure of Brahman-bliss is guarded within the self, encircled by the mighty, terrible serpent of egoism with its three fierce heads made of the guṇas. Having, with the shining great sword called knowledge, severed the three heads and uprooted the serpent, the wise one is able to enjoy this happiness-bestowing treasure.