As a young person with a growing interest in photography, you'll eventually want to buy a second lens for your camera. Good lenses are expensive, so you'll need to know enough about them to make an informed choice. If you buy a good lens and take care of it, you'll be able to enjoy it for decades.
Different lenses accomplish different goals.
For example, you shouldn't use the same focal length to photograph a basketball game, a close-up of a flower, and a landscape. In other words, no one lens is right for every type of photography. As your experience broadens, you'll want to own a variety of lenses, each best suited for a particular job. A 90 mm is fairly long. The longer the lens, the farther away you'll stand from your subject to take the picture.