I'm looking at the monk and it lists the different fighting stances. However under all their traits it lists 'non-lethal'. Does this work the same as in PF1? So any attacks I make are separated from lethal attacks and only do damage under the 'non lethal' column? So I can only knock someone out at the most but my allies may be attacking as well and doing lethal damage which doesn't contribute at all to the 'non lethal' you are doing?
Could anyone clarify this for me.
So this is slightly complicated because it's in 3 places in the book, but in the end it works how we'd like it to.
So first off the nonlethal trait does mean: "All attacks with this weapon are nonlethal" (p. 182) but also directs to page 294 which says "Likewise, you can attempt lethal attacks with a weapon that has the nonlethal feature, also calculating your attack roll’s result as though you were untrained."
So now flipping back to the class section under Monk, the Powerful Fist ability (p. 97) includes the sentence "You use your normal proficiency when making a lethal attack with a nonlethal unarmed attack."
So with all of this working together a monk, who is using an unarmed attack (any strike with the unarmed trait, including stance-based ones) can choose whether to do lethal or unlethal damage with their attacks use the same proficiency modifier to their attack roll either way. Someone without an ability like this using a nonlethal weapon, will take a -4 (untrained proficiency penalty) to attack rolls if they want to do lethal damage or a if they are wanting to do nonlethal damage with a weapon which lacks the nonlethal trait they will similarly take a -4.
So monks are exceptionally good at alternating between lethal and nonlethal damage depending on what circumstances warrant (the axe fighter in your party doesn't have an easy time fighting people you do not want to kill.)