Srila Gurudev explains who Purushottam is. Krishna Himself instructed us in Srimad Bhagavad Gita, "I am beyond the comprehension of the mind, intelligence and senses of the conditioned souls of this world. I am the Supremely superior to the formless impersonal brahman and also Paramatma, the object of worship of gyānis and yogis, so I am called Purushottam." So Purushottama is the Supreme Lord Sri Krishna Himself. Also, the fountainhead of all incarnations, the Supreme Lord Sri Krishna appeared in this special Kaliyuga, taking the mood and complexion of His internal potency Srimati Radharani, as Sri Chaitanya Mahaprabhu, He is also Purushottam. He is identical with Krishna. Lord Jagannath, who resides in Puri Dham is also Purushottam, He is Krishna Himself. So we have to serve Sri Krishna, Lord Sri Chaitanya Mahaprabhu and Jagannathdev in this holiest month.