द्वाविमौ पुरुषौ लोके क्षरश्चाक्षर एव च। क्षरः सर्वाणि भूतानि कूटस्थोऽक्षर उच्यते ॥

dvāv imau puruṣhau loke kṣharaśh chākṣhara eva cha kṣharaḥ sarvāṇi bhūtāni kūṭa-stho ’kṣhara uchyate

There are two Energies in this world, the destructible and the indestructible; the destructible is all beings, the unchanging is called the indestructible.

In plain words: Krishna says there are two kinds of being in the world. All living creatures are perishable, and the unchanging part behind them is called imperishable.