Having a deep depth of field is to have a large amount of the image in focus.

When the aperture is small (ex. f/16), the image has a deep or large depth of field. This means that the focus range covers a large area front-to-back, from several yards in front of the focus plane to nearly infinity behind it.

Large depth of field is most often associated with landscape photography, but you can also see it in architectural photography. It is also known as the storytelling DOF because you can have multiple visual storylines or characters at various points of the photo.