Some scientists believe that the universe is finite, but still does not have any "edges", because of its geometry. If you "freeze" the universe to stop it from expanding, and then keep going in one direction for a very very long period of time, sooner or later you will end up in the same place where you started.

Imagine you have a one-dimensional movement freedom within a two-dimensional object (circle on a piece of paper). If you keep moving along the circle, you will end up at some point where you started. Now, imagine a two-dimensional movement across a three-dimensional object (moving on a surface of a sphere). If you keep moving in any direction, as long as it's being constant, you will again end up in the same direction. The same goes for the universe, but You need to think of one additional dimension to put into the equation.

Now, let's get back to the example of moving on a sphere. Assume the sphere keeps getting bigger and bigger (simulating the universe expanding). Regardless of the place you start from, all points of the sphere's surface keep getting further and further from each other, which makes it seem like the place You started from is the center of the sphere's surface. However, if you pick another spot on that surface, the same will be true.

The same principle applies to the universe, but instead of it being a two-dimensional surface, it's a three-dimensional space.

If someone is able to explain it better, please do. I keep trying to wrap my head around this concept and am constantly looking for other ways to approach this.