You can indicate if the image is for decorative purposes only. That means that it will have an empty alt text so that screen readers ignore it. It will also not have a caption.
Use this option only sparingly for truely decorative images such as a border or an image of glitter.
Typically, images should have alt text to describe what is shown in the image as that helps people using a screen reader to perceive them.
Images don't necessarily need a caption.