My perscription says take one tablet three times daily for breakthrough pain so does that mean i?

I would like to chime in an add that if you are having breakthrough pain, before taking the medication prescribed for the breakthrough pain, stop, think, and quantify (using the Pain Scale 1-10) if you desire, just how much do you really need it. If you do decide to use it, a combination of these two drugs is likely to cause nausea, so eat a little something before taking. In other words, what I am trying to express is, please do not take these freely. Use caution.
Best Regards.

It means take it 3 times a day prn(as needed). If you arent having pain then you don't need to take it.

Not necessarily. It is for breakthrough pain. If you are not having breakthrough pain then you dont need to take it at all. If you are having breakthrough pain you can take one tablet up to three times a day. You may need only one or two or even all three depending on your pain. Breakthrough pain is pain that is over and beyond what your regular long acting pain should control. You should be getting most of your pain control from your long acting drug. If you do an activity that brings additional pain you can use a breakthrough pill or some tend to need a breakthrough pill as it gets near to the end of their dosing cycle but is too early to take the next dose of long acting drug. Does that help?

No, what that means is that if you have the pain you can take 1 tablet three times a day (in divided doses eg breakfast, lunch & diner).
If you are pain free then there is no need to take the tablets.