An engine swap is when you take out the engine from your car or vehicle and replace it with a new, different one. People do this if they want more power or if their old engine is not working well anymore. It's like when you trade your toy car for a new one with more awesome features.
But unlike trading toys, engine swaps can be complicated and require a lot of work. You have to make sure the new engine fits in your car and that all the parts connect properly. It's like fitting together the pieces of a puzzle.
Engine swaps can also change the way your car drives and handles, like how your toy car might drive differently with a new engine. That's why it's important to do research and ask experts before swapping an engine.