Imagine you have many toys scattered throughout your room and your mom wants you to clean everything up. You can either take one toy at a time and put them in their proper place, or you can divide the toys among you and your three friends, and each of you can work on putting away toys at the same time. This way, you can finish cleaning up more quickly and efficiently, and maybe even have some extra time to play with your friends once you're done.
Multi-core computing works the same way. Instead of having just one brain (processor) doing all the work when you use your computer, you have multiple brains (cores) working together to get things done faster. Each core can handle a separate task or part of a bigger task at the same time, so your computer can perform more tasks simultaneously with less effort. This makes everything from running large applications like video editing software to opening multiple web browsers faster and smoother.
In summary, multi-core computing means having multiple processors (cores) working together to handle tasks more efficiently, just like how you and your friends can work together to clean up your toys more quickly.