The exposure triangle is a using aperture, shutter speed, and ISO in the exposure of a photograph. You must balance all three of these to get the desired photograph an adjustment of one aspect requires adjustments of at least one of the others.
Shutter speed is the amount of time light is allowed in the camera, when a camera's shutter is open when taking a photograph. The amount of light that is allowed in the lens is proportional to the exposure time.
Aperture is the opening of a camera. How much light that is let in to the camera is dependent on the aperture. A large aperture has a small f/stop. And a small aperture has a large f/stop. Large apertures allow an abundant amount of light in. Small apertures allow less light in. Wide depth of field is obtained when using small apertures, or a larger f/stop. Shallow depths of field are required for large apertures with small f/stops.
ISO is an artificial light. If you have a greater ISO your image will will be bright and grainy. You want a higher ISO in low lighting. If it is bright and sunny you want to set your ISO as low as possible, as your image will be of a greater quality. In general you want a low ISO because your images will be better, a high ISO will make your image lesser in quality but is a necessity in low light situations.
White balance is the temperature of the colors in you photo. It changes how light affect the color of your final image.