A local homeomorphism is when you have two spaces (like a square and a circle) and you can stretch and squish them as much as you want (without breaking them or making them cross over themselves), as long as all the little parts (like points or tiny lines) still line up correctly. It's like when you draw a picture and you can make parts of it bigger or smaller, but everything still looks like it fits together.
A good way to think about it is if you imagine a map of your neighborhood. Each street has a name and a certain shape, but you can change the size of the map and zoom in on different parts without changing the structure of the streets, houses and buildings. In this case, the map is a local homeomorphism, because you can still follow the same directions and find your way, even if you're looking at a smaller or larger version of the map.
This concept is important in math because it helps us understand how different spaces (like a square and a circle) can be related to each other. Local homeomorphisms are useful for mapping one space onto another and preserving important properties like distance or connectedness in topology, which is the study of how shapes and spaces are related to each other.