सहयज्ञाः प्रजाः सृष्ट्वा पुरोवाच प्रजापतिः। अनेन प्रसविष्यध्वमेष वोऽस्त्विष्टकामधुक् ॥

saha-yajñāḥ prajāḥ sṛiṣhṭvā purovācha prajāpatiḥ anena prasaviṣhyadhvam eṣha vo ’stviṣhṭa-kāma-dhuk

Having in ancient times emanated mankind together with sacrifice, the Lord of emanation said: "By this shall ye propagate; be this to you the giver of desire;

In plain words: Krishna says that long ago the Creator made people along with sacrifice, or giving offerings. The Creator told them that through sacrifice they would grow and get what they wish for.