What does it mean when the "heads on your car need to be resurfaced"

[poehitman]

I'm looking to buy a 93 T-Bird but the seller said the "heads need to be resurfaced". I don't know what that means. Any help?

 

[poehitman]

Also, here is a question. I wrecked my 95 T-Bird (slid into a wall at 25mph in the rain). The 93 I was looking at is a 3.8L SC and mine is a regular 3.8L. Would it be possible to take the heads out of my 95 and put them in the 93?

 

[BadMofo666]

It means the heads have been warped, due to heat, or just time. And your other heads should bolt on but they may be a little different causing a performance difference, maybe good, maybe bad.