A mesoporous material is a special thing that scientists make in a lab. It's a really tiny material that looks like a sponge. But instead of holes you can see, it has really, really, really tiny holes that are so small you can't see them with your eyes. It's like when you pour water in a sponge and it goes inside all the holes, except the holes in a mesoporous material are much smaller.
Scientists make the mesoporous material by mixing a special liquid with tiny particles called nanoparticles. The liquid and particles join together to create the sponge-like material, with really tiny holes.
The cool thing about mesoporous material is that it can be used to store things that are too big to fit through the tiny holes, like medicine molecules. The medicine will sit on the edges of the holes and will be protected inside the sponge. Scientists can also change the size of the holes to make the material specific for different medicines or other things they want to store.
So, in a nutshell, a mesoporous material is a really tiny sponge-like material with really tiny holes that can store medicines and other things.