What is the "Exposure Triangle?"
That means that the larger the aperture, the less depth of field you will see. If you have a smaller aperture, your depth of field will be larger. To see a single item with a blurry background, use a high aperture. If you want the entire picture to be clear, use a low aperture.
The larger the f-stop (aperture measurement), you will have more depth of field but a small aperture. The smaller the f-stop, you will have a lesser depth of field but a large aperture.
You want to use a fast shutter speed if your object is moving, which will freeze your image, while if your object is moving, you want to use a slower shutter speed to blur your image.
You would want to use a high ISO on a dark/cloudy day, while if the sun is shining, a low ISO would be best.