Imagine you are playing with your toys in a big room, and you want to know how to get from one toy to another toy. You can walk on the floor to get there, but what if you wanted to go faster and jump over things? You would need to add a new dimension to your play space, like jumping up and down.
Minkowski space is like that, but for space and time. Instead of just three dimensions (up-down, left-right, and forwards-backwards), we add a fourth dimension for time. This allows us to connect points in space and time in new ways, like jumping through time.
Minkowski space is named after Hermann Minkowski, who first came up with this idea. It is used in physics, especially in the theory of relativity, to describe how things move and interact in space and time. So just like in your playroom, Minkowski space adds more ways to move around and explore our world.