"Environmental conservation" is the broad term for anything that furthers the goal of making life more sustainable for the planet. Ultimately, people want to help the planet survive naturally and with no negative impact from the human race. Helping keep the planet safe and healthy is called "conservation."
Environmental conservation comes in many different types because it is a topic with a lot of areas to cover. There are interest and effort groups formed around each topic to help break it down and make it more manageable. For instance, there are groups that help clean up the oceans, replant trees to build up the forests, stop harmful deforestation and land development, and educate children and adults about how to take care of the environment.
Environmental conservation includes taking care of the air and the earth's atmosphere, animal and plant life, humans and cultural development, and the planet's water. It shares a lot of interests with human rights, because keeping underprivileged populations healthy and thriving has a lot to do with preserving the earth. Conservation can be as little as planting a tree and maintaining it or as big as saving a species of whales. The main idea is that any progress is good progress, no matter the size.