'Sustainability' means using the world's natural resources in a way that means they will last for future generations. It means that we need to make sure we're not going to use them up, run out of them, or make them go extinct.
We support Sustainable Development Goal 15 because we care about flora and fauna and want to see all life on earth protected. We want to make sure that the world we grow up in is safe and beautiful for us just like it was for generations past. We want to stop the extinction of more flora and fauna.
Braidwood is a rural area. Many people in Braidwood live a life on the land. They are farmers and gardeners and need to make sure that the land can continue to meet the needs for their cattle, sheep and crops. If our society doesn't look after the land it might find that in years to come our fruit trees will not grow, and our cows and sheep do not have enough food to eat. This would not be good for anyone.