Becoming a vegetarian or vegan may benefit you and animals in more than one way. First of all, you will help to save the lives of animals. Also, you may be improving your health.
Being a vegetarian or vegan helps animals and the environment. Many slaughterhouses treat their animals inhumanely, giving them very little space to move around. Also, tropical rainforest is sometimes cleared to make room for cattle to graze. Once the rainforest is cleared, the thin layer of topsoil has little protection from the rain, and is quickly washed away. The soil is then useless to all life.
There are different types of vegetarians. Lacto-ovo vegetarians don't eat meat, but they do consume dairy and egg. Lacto vegetarians eat dairy but not meat or eggs. Ovo vegetarians eat eggs, but they don't consume meat or dairy. Vegans don't consume any animals products. They don't eat meat, eggs, or dairy products.
There are many foods out there made for vegetarians and vegan which don't have meat or any other animal products in them. Companies have come out with food made from soy which looks and tastes a lot like meat. This includes, veggie burgers, soy "lunch meat", and soy "chicken". For vegans, there are different brands of soy cheese and soy milk.