How does a pineapple die does it rot or something?

Pineapples aren't living things, so they don't die. They do rot if not eaten within an appropriate amount of time once they're picked.

Pineapples are living things but Alty is right that saying they don't 'die', that's not the correct term as it is a fruit and hence once picked then starts to rot

Are you maybe talking about a Pineapple plant? If so.. than yes it would die maybe because it rotted. I have had some do that.:)

Yes, pineapples are a part of a living thing, a tree. It's fruit though, not a human, not an animal, and not capable of "dying".

Can a tree die? Yes. Can fruit die? No.