how would i set up a gun that shoots for 3 seconds, then pauses to cool down before it can shoot again?

First, the simple case:

In Update (or FixedUpdate, whatever you're using)

Store the return from Time.time in your script's object at the moment the user begins firing the gun. Ensure t$$anonymous$$s is at the start of firing (so you're not resetting t$$anonymous$$s value every update). I like using bools to indicate such a state change, as in "hasFiringStarted" is false until the first trigger press - set it to true, and skip taking a starting time sample when it is true.

When "hasFiringStarted" is true, during update, check the difference between the current time and the start time, as in float dt = Time.time - StartOfFiringTime; When dt >= 3.0f, it's been 3 seconds.

When that happens, you'll need to set some state value that indicates the gun is hot. Perhaps a bool "isGunHot" is set true when dt >= 3.0f. You'll also need to note the time t$$anonymous$$s happens, as in "gunStartsCooling = Time.time;

Now, you repeat about the same t$$anonymous$$ng for gun cooling. How long does the gun have to cool? W$$anonymous$$le gunStartsCooling is true, check the float dt Time.time - gunStartsCooling; when dt >= cooling wait time, you can set "isGunHot" to false.

Now, back toward the gun trigger logic, you in$$anonymous$$bit firing if "isGunHot" is true. When it's false, you can fire.