In photography, 'exposure' means the amount of light that hits your sensor.
Your shutter speed will help decide how much light hits the sensor. Fast shutter speeds only allow a fast burst of light on to the sensor which means that your image will be crisp in quality and have a lack of motion blur. Slow shutter speeds allow the shutter to stay up for longer which means that more light will be captured and result in a lot of motion blur.
ISO is the sensitivity of the sensor to light. High ISO will mean that the sensor is more sensitive to light (3200 ISO). A low ISO will mean that less light is hitting the sensor (100 ISO). High ISO is useful in dark conditions however, it will make the image grainy if it is too high. A lower ISO is great in light conditions such as a sunny day.
Night photos that I took for Jarrods half term set homework.