It's the power ranking "score" for each team. Basically, on a neutral playing field, if two teams are playing each other, the final score differential should be determined by the difference of the two team's scores. I decided to expose that number to give a better idea of the distance between two teams in the power ranking algorithm.

The score is basically the numbers each team is assigned to get the lowest error rate when running that algorithm over all the games used to generate the score (with a 3-point HFA).