Ok kiddo, imagine you have a big balloon and you start squeezing it in the middle. The air inside the balloon would start to move away from the middle and towards the sides. This is what happens in the earth's atmosphere too. Sometimes, there are areas where the air is moving away from the middle like in the balloon. These areas are called low-pressure areas.
You know how it feels like when you blow into a straw and the air comes out with force? It's similar in a low-pressure area. The air from high-pressure areas all around the low-pressure area comes into the low-pressure area with force. This movement of air can cause things like wind, clouds and even storms.
So, just like how the balloon changes when we squeeze it, the earth's atmosphere changes when there's a low-pressure area. It can even affect the weather and how we feel temperature, so it's important to keep an eye on these areas.