Training: You'll be able to distribute the 25 training point in the various categories. Every one improve a single stat of your boxer, up to his maximum potential. Every boxer has an actual skill and a potential skill. His actual skill can never be higher than his potential skill. If you don't train your boxers, their stats slowly decrease.

Boxer Condition: Fitness is really important, if it is too low your boxer can't fight. This value is usually at zero after a fight but slowly increase month by month Morale is important too, but a boxer can have a fight even if his morale is broken (he won't fight so well of course).

Rankings: and you'll see the rankings for your currently selected boxer. By default, when you enter this screen, your first boxer is shown.
If you simply want to look at rankings for the 17 different weight categories, you need to use the left-right arrows on the left-top part of the screen.
Remember that there are various weight categories, so you can have one boxer rank 70 in Strawweight and another rank 90 in Heavyweight.

From this screen you can also arrange a fight. On the list on the right, you'll see a red flashing name: that is your currently selected boxer. You can arrange a fight with another boxer of the same category, if the rank difference is no more thank 5. For example if your boxer ranking is 95, you can challenge another boxer up to the rank 90.