Yeah you can hover your mouse over anything in the script and it will explain what's going on.

The Action Penalty (AP) can never be fully trained off, the best you can do is reduce the penalty by 50% by training in armor use.

Full Leather has an AP of -1 so you can never make this better since again you can't bring it to 0 and there are no half points here.

Double Leather has a base AP of -6. You can train off 1 point for every 50 ranks above what you need to train off the RT penalty. So since Double Leathers requires 6 ranks to train off the RT penalty, that means you can train off 1 AP at 56 ranks, another at 106 ranks, and the last one at 156 ranks.

Pures typically don't bother training off AP, that's more of a semi/square thing, but you can do so if you choose. Although I would make that a post cap goal if you plan on doing it at all.