The human body has way more than 5 senses, which helps us feel, experience and understand our environment. They are the medium for us to reach the world and better understand it, but how could we be sure of what we see or what we feel? How could anyone be sure of anything? We have way more than five senses, we have at least twice as much and then some. But they're not perfect. There are optical illusions, audio illusions, temperature sensation illusions, even tactile Illusions.
Every day our limits of our senses are tested. For example, if you look closely at the picture below your brain will will interpret it as a colored image, but actually it is a black and white with a grid of colored lines overlaid upon it. Our senses are the only tools we have to get what's out there and if even they could be flawed, so easily then do we actually know anything?
The study of knowing is called Epistemology. Plato famously said " The things we know are things that are true, that we believe and that we have justification for believing."
There are things that we can know without needing proof, without needing to even leave the house, things that we can know as true by reason alone. An example would be the statement "all bachelors are unmarried." I don't have to go survey every bachelor on earth to know that that is true. All bachelors are unmarried because that's how we define the word bachelor.
Coming back to the question, The world is real, right? How do you know? It's a difficult question, but it's not rocket science. Instead, it is asking whether or not rocket scientists even exist in the first place.
The theory that the Sun moved around the earth worked great. It predicted that the Sun would rise every morning and it did. It wasn't until later that we realized what we thought was true might not be. So, do we or will we ever know true reality or are we stuck in a world where the best we can do is be approximately true? Discovering more and more useful theories every day but never actually reaching true objective actual reality. Can science or reason ever prove convincingly that your friends, your fingers actually exist beyond your mind? That you don't just live In the matrix?
Your mind is all that you have, even if you use instruments, like a telescope or particle accelerators. The final stop for all of that information is ultimately you. You are alone in your own brain, which technically makes it impossible to prove that anything else exists. It's called the egocentric predicament. Everything you know about the world out there depends on and is created in your brain. The belief that only you exist and everything else, food, the universe, your friends are all fragments of your mind is called solipsism. There is no way to convince a solipsist that the outside world is real. On the contrary realism is the belief that the outside world exists independent of us. Rocks and stars would continue to exist even if you weren't around to experience them. But you cannot know realism is true. All you can do is believe.
Humans have a very distinctive character which makes them different from other mammals. They are curious beings. They have a thirst to understand everything. But We will never be able to understand all of our questions and phenomena is our universe.. We won't be able to ever answer every single question, but walking around in those questions, exploring them, is what we love. It's not the answers which makes us different, but the questions we ask.