Camera is a machine and many times, it doesn't understand what is in front of the lens. It is programmed (particularly in AUTO mode) to take say x amount of light (light is measured in Lumen but it is hard to interpret). So on a beach when everything is too bright, camera tries to take in x amount of light but that is too less to properly expose human faces. That is the reason we look darker on a beach, on snow or on a bright day. Opposite happens in evenings or in dull light. Camera tries to take in x amount of light but that exposes the faces too much causing people in the photo to be washed out.
Probably you are not aware but somewhere on your camera, you will see this icon or a button with + and - minus sign as shown below. It is called EV (Exposure Value) button or Exposure Compensation button.
Please note that some cameras don't allow EV compensation in AUTO mode. If this is the case, hopefully, your camera has P (Program) mode and you can use it with EV compensation.
Sometimes it is also referred to as Exposure Bias. Click on it and it will open up a scale or a value on your LCD.