[cannon_gray (Cannon Gray)]

Well, there are two answers to your question: "Really big" and "We can't actually know."

The first answer is regarding what we call the "observable universe." This is the part of the universe we can see and interact with, and it includes billions and billions of galaxies, each comprising billions and billions of stars, and many of those likely accompanied by some kind of planetary body or bodies.


The second answer is regarding whatever lies beyond the observable universe. Grossly simplified, our current understanding of physics suggests that information cannot travel faster than the speed of light. That means everything we can know about lies within two 4-dimensional cones, one pointing into the future and the other pointing into the past. This is called our light cone. We are pretty sure there is more universe beyond our light cone, but we literally cannot say with absolute certainty because that part is beyond what we can observe.
The universe is certainly huge, and it might be infinite, but we can't say for sure.