Imagine you have a bunch of toys to play with, but you can only play with one toy at a time. When you're done playing with that toy, you have to put it away and take out a new one to play with. This takes a lot of time and can be frustrating.
Now imagine that instead of having to put away one toy and get a new one every time, you have a few toys already out and ready to play with. When you're done with one toy, you put it back in a toy box and take out a new one that's already been prepared for you. This saves time and makes it easier to keep playing.
The object pool pattern is a lot like having a toy box. Instead of constantly creating and destroying objects (like toys) in a computer program, a few objects are created ahead of time and put into a pool. When the program needs an object, it takes one from the pool and uses it. When it's done using the object, it puts it back into the pool for later use. This saves time and resources because the program doesn't need to constantly create and destroy objects.
So basically, the object pool pattern is like having a toy box for objects in a computer program. It makes it easier and faster to use objects without always creating new ones.