Aj Edwards

So, I just got arma 3 as a gift to play with my friend but he hasn't even jumped on it since. Free game I guess. But I've tried asking him several times what arma 3 is about, because Im completely ignorant to the series. I just know its about warefare, but I see others saying its about survival. I've seen a few mods like exile, epoch and ryans zombies that I really like and i have them and several other mods now, but I want to know if there are any guidelines? Like.. can I just join the server that says pvp or pve, kos or no kos, and treat it like ark? just jump in, gear up and kill players or ai (if the server allows pvp)? Also, I'm sorry if this is the wrong place to post this!