Okay, so have you ever seen those pretty paper decorations that look like hearts but they're not flat, they're all bumpy and have lots of folds in them? That's called a pleated heart!
Basically, you take a rectangular piece of paper, fold it a few times, and then make lots of little accordion-like folds with it so it looks kind of like a fan. Then you pinch one end and push the other end in to make it bend into a heart shape.
People like to make pleated hearts for Christmas because they make pretty decorations you can hang up on the wall or put on the tree. Plus, they're fun to make! Just be careful not to get any paper cuts from all that folding.