Help Please

Hello everyone my name is Michael Russell I am an electrician by trade and i am coming up on my construction retirement plan next year, i am now trying to become a building inspector, my question is can some one explain a few of these charts for me, such as roof sheathing span chart ( i am not sure what the numbers mean) and Maximum Post Height Chart (Species section) which species?

Post the charts please.

It would help if we can see the charts that you are looking at. if they are online give us a location.