Negative space is when you have a picture that has one main part shaded in or around the picture. Just look at my image, see how the green gives out the shape of the bird. The green is the positive space and the black is the negative space.
I found negative space by tracing out the outline and moving key detailed parts to give it it’s dimensions.
It helps them by giving them the shape of the image so now they can later add detail.
Yes it gives an overview of the image.