SB 5.18.35
om namo bhagavate mantra-tattva-lingaya yajña-kratave maha-dhvaravayavaya maha-purusaya namah karma-suklaya tri-yugaya namas te.
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
O Lord, we offer our respectful obeisances unto You as the gigantic person. Simply by chanting mantras, we shall be able to understand You fully. You are yajña [sacrifice], and You are the kratu [ritual]. Therefore all the ritualistic ceremonies of sacrifice are part of Your transcendental body, and You are the only enjoyer of all sacrifices. Your form is composed of transcendental goodness. You are known as tri-yuga because in Kali-yuga You appeared as a concealed incarnation and because You always fully possess the three pairs of opulences.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Sri Caitanya Mahaprabhu is the incarnation for this Age of Kali, as confirmed in many places throughout the Puranas, the Mahabharata, Srimad-Bhagavatam and the Upanisads. The summary of His appearance is given in Caitanya-caritamrta (Madhya 6.99) as follows:
kali-yuge lilavatara na kare bhagavan
ataeva ‘tri-yuga’ kari’ kahi tara nama
In this Age of Kali, the Supreme Personality of Godhead (Bhagavan) does not appear as a lilavatara, an incarnation to display pastimes. Therefore He is known as tri-yuga. Unlike other incarnations, Lord Sri Caitanya Mahaprabhu appears in this Age of Kali as a devotee of the Lord. Therefore He is called a concealed incarnation (channavatara).