Puja is a word in Sanskrit language. In Sanskrit, words are formed with meaning in mind. The 'p'  removes all accumulated sins, and  'j'  makes your life's purpose fulfilled

To attain the blessings of God, Hindu philosophy advocates two paths :

GYAN : Path of Wisdom

BHAKTI : Path of Devotion.

The Pooja, when done properly guides oneself towards God, and while doing 'Prarthana' (praying), the Supreme Being draws closer to the devotee.