Think of the environment as everything that is around you. A quiet room with good lighting and no distractions is a good environment for doing homework, or at least that's what your parents and teachers think.
Environment generally refers to your surroundings. If something is good for the environment, it is beneficial to the complex system of plant and animal life, water and air on Earth. An environment need not be so large, however. The environment of your living room means the tables, chairs and decor that are in the room. Sometimes it refers to the general attitude of a place. Do you thrive in a competitive environment or prefer an atmosphere of cooperation?