What do these 3 lines mean in dantes inferno first chapter?

In the tercet you have chosen, Dante is inching his way up a slope toward a hill by planting his bottom foot firm and pushing off to advance, as you can see in the last line of the tercet mentioned. This most likely is representetive of the Christian tradition for such a difficult progress toward one's goal, which you can find in St. Augustine, who for a long time remained a Catechumen before he chose his life in Christ. It can likely be said that Dante moves forward with his right foot, representing intellect, supported by his left foot representitive of will. It can also represent a limping man, wounded in both his feet by Adam's sin.