What does father of federation mean?

The term "Father of Federation" refers to Sir Henry Parkes, an influential politician who pushed for Federation of Australia's states. To be the "father of federation" means he was the one who really pushed for the federation of Australia's colonies.

Parkes is particularly remembered for his famous Tenterfield Oration, delivered at the small rural town of Tenterfield in October 1889. In this speech, he campaigned heavily for Federation of the six Australian colonies. Tenterfield was selected as the place to make his stand as it was part of New South Wales but a long distance away from Sydney. This meant that the town was disadvantaged by the steep tariffs imposed on the transportation of goods across the border to Queensland, where the closer trade centre of Brisbane was located. His promotion of Federation was based on the fact that it would enable free trade across the borders.