When it's time for a fight or there's imminent danger, the cadence of the conversation becomes discrete, and action is handled on a turn-by-turn basis. You enter encounter mode by rolling for initiative, and the types of actions you can take happen only on your turn in the round, all of which is further described in the rules for Combat & Tactics.
On your turn, you may take one of the actions below (or any one of the actions described in exploration) and move one melee space (this is your movement rate), but you cannot Dungeon Crawl, Give Chase or Flee, or engage in Social Combat that may take more than a single round to complete.
Attack
Use your weapon or maleficence to deliver harm or inflict a peril.
Cast
Use your magic in the form of a sorcery, psionic, or thaumaturgic spell.
Dodge
Spend your turn focusing on dodging attacks to improve your defense in the round.
Deflect an attack with a weapon, maleficence, or shield. You can also sacrifice your shield to parry an attack.
Perform
React
Act in response to someone else's action, outside of your turn if you have an ability that allows you to do so, such as the class ability Arcane Adept or the kit ability Swashbuckler.
Run
Move one encounter space instead of a one melee space. If your movement rate is 0, you cannot move beyond your personal space.
Use
Use an item that requires finesse, such manipulate a magic item that requires activation; equip armor or shields; or read a scroll.
Give Chase or Flee
Elude or pursue a foe. While giving chase or fleeing, you may be required to make multiple checks to complete the chase.