Felling means cutting down trees. It's like when you use scissors to cut paper but instead of paper it's a really big and tall tree. People cut down trees for different reasons, like to make wood for building houses, paper, or furniture. Sometimes, trees have to be cut down because they're old and not healthy, or because they're blocking a road or power lines. But it's important to remember that trees are also really important for our planet, they produce oxygen, and provide habitats for animals, so we need to be careful when cutting them down and make sure we always plant new trees.