ISO – this changes sensitivity of the film
The lower the setting the less sensitive the film is and the more light you will need. The higher the setting, the more sensitive the film and the less you light you will need.
ISO 100 – 400: for outdoor sunlight use. 800 is for low sunlight.
ISO 1000 and above: low light and evening light.
Aperture- This setting changes how wide the aperture of the lens is. The lower the setting, the more light is let into the lens. The higher the setting, the less light is let into the lens. F1.8 is used for darker conditions but also creates a narrow field of focus. F5.6 and above are used for lighter conditions and create a wider field of focus.
Shutter speed- How fast the shutter opens and closes. The faster the shutter speed the clearer and less blurry the image is.
For example to create a narrow field of focus in day light conditions you would need to use a medium ISO setting and a low Aperture setting.