What does the phrase When a coin into the coin box rings a soul from Purgatory soon will spring mean?

This is a reference to the Dominican Friar Johann Tetzel and his propagating of the idea of Indulgence as outlined by Pope Leo X in the 16th C. Charged by the Pope to raise money for the reconstruction of St. Peter's Basilica in Rome, he manipulated the lay community by stating that they could pay to have their dead loved ones souls released from the temporary suffering of purgatory and ascend straight to heaven. Essentially, you could buy your way into heaven.