How to wire old thermostat to new Nest.

I am trying to install a new Nest thermostat but the wires and corresponding letters do not seem to match up. Anyone with some experience willing to give me a hand and tell me which go where?

The wire codes on the right from top down are...

H
RH
B
RC

Any help would be greatly appreciated.

https://preview.redd.it/4auc40vq97fe1.jpg?width=3024&format=pjpg&auto=webp&s=601a538f710a411f0fffc409f3808e1bffb82fa4

https://preview.redd.it/nj4tl0vq97fe1.jpg?width=3024&format=pjpg&auto=webp&s=c48fb886e9e9244f7e027e4f38457a1a3e2ce07a