Proportional Representation eliminates the concept of having a single representative in the House for each district. Instead, there would be some larger number, (10 for example). That number of representatives would be evenly divided based on the vote share given to each political party. Instead of a situation in which Democrats receive 42% of the vote and 0% representation, while 58% of the voters (Republicans) receive all of the representation, we'd shift to allow for the election of 4 Democrats and 6 Republicans.
This would result in a much more representative government and increased fairness wherever implemented, eliminating concerns over redistricting.