Pollution is when people or things make the environment dirty. Imagine if you lived in a house and you didn't clean up after yourself, your toys were everywhere and there was trash all over the place. Your house would be polluted and it would be difficult for you to live there happily and healthily.
This is similar to what happens to the air, water, and soil around us when people and things pollute it. For example, when factories release smoke into the air, it makes it hard for people to breathe and can cause health problems like asthma. When people throw garbage into the water, it can make it unsafe for fish and wildlife to live there. Or when people use pesticides and fertilizers on crops, it can seep into the soil and pollute it.
It's important for us to take care of our environment and not pollute it because pollution can cause harm to ourselves and other living things around us. We can do things like use less plastic, recycle, and pick up litter to help reduce pollution. By taking care of the environment, we're making sure that our planet stays healthy and safe for all of us to live on.