What does "Five hundred, seven-point spread" mean?

This except comes from the novel The Shining:

The manager was a man named Queems, and when Hallorann came in Wueems was conversing with his bookie. He wanted the four-horse at Rockaway. No, no parlay,no quinella, no... Just the little old four, six hundred dollars on the nose. And the Jets on Sunday. What did he mean, the Jets were playing the Bills? Didn't he know who the Jets were playing? Five hundred, seven-point spread.

What does "Five hundred, seven-point spread" mean here?

Thank you.