Classes, Multiclassing and Prestige Classes — Glossary

You reduce hit roll based damage by the armor value reduced by armor piercing value

Dodge is the value required to hit the target. If your dodge is higher than the attack roll, the attack misses. Dodge is calulated by (10 + dexterity modifier, to a max of the lowest dex_cap from armor or shield) + your proficiency(proficiency tier + half level, rounded up)

Expert proficiency tier provides a +5

trained is the lowest tier of proficiency, you gain a +2 + half your level rounded up to it.