What is beyond the universe?

Could you elaborate on the concept of what lies beyond the universe? Is it a realm that exists outside of our observable cosmos, or is it something more abstract and theoretical? Are there any scientific theories or hypotheses that attempt to explain what might exist in this elusive realm? And if so, what are some of the key ideas and concepts that underpin these theories? Ultimately, what are the implications of understanding or not understanding what lies beyond the universe for our understanding of the Cosmos and our place within it?