Okay kiddo, imagine you and your friend are playing a game where you have to hold your breath for as long as possible. If your friend takes a big breath and then says "ipso facto, I win," it means that they won the game automatically because they did something that made them the winner without any other action needed.
"Ipso facto" is a fancy Latin phrase that means "by the fact itself." It's a way of saying that something is true or happened because of another thing that happened before it. So if your friend took the biggest breath, it made them the winner of the game "ipso facto" - by the fact that they took the biggest breath.
People often use "ipso facto" to explain something that's really obvious, like saying "I'm really thirsty, ipso facto, I need a drink." It's just a fancy way of saying that something is true because of something else that already happened.