What exactly are you not understanding?

It just shows current status/next status and expected dates of training/transfer.. not much to it really.

There is also a key at the bottom..

If you are looking to base trade to LFE for example you can look at the flow plan and count how many people are transferring out/in and upgrading along with the expected class/transfer dates to get an idea of where you will be at. Or if you are awarded a new status you can see the expected dates and who else will be in your class. One thing that is kind of annoying is its all out of order.. so you pretty much have to go through the whole thing if you are trying to do any math with it.