A universe that is fine-tuned is a universe that is designed well-enough to support life. Life as we know it would be impossible if certain things in physics were slightly different. Our universe is fine-tuned for life, and this is seen as not likely. This is because many things have to come together in a certain way. One explanation for this is the anthropic principle. This means that the universe supports life because we wouldn't be here to wonder that if it didn't. This usage of the anthropic principle is tautological. This means that it is true because it is true.