Visual intelligence, as a component of the Howard Gardner's theory of multiple intelligence, consists of the abilities and skills related to the ways of visualizing and perceiving the world analytically and synthetically to sharpen critical and creative visual thinking to construct and articulate knowledge, as I could gather as an educator.
It is related to mental visualization and training of the eye for details through reading visuals and creating visual material as well as enhancing the situational or spatial awareness.
Here is an ABC verse on visual-spatial Intelligence.
ABC Verse
A: Assessing objectively a physical or spatial situation or what you see and articulating it to create a vivid picture
C: Creating and recreating visual experience from perceptions and situational awareness to deepen insights and not to judge
B: breaking down information in visual and text codes as in a sketch note for attentiveness and cognitive gains including development of photographic memory
D: Developing designs and visually supportive learning material and utility items
E: Enjoying various visual experience and over-learning three or more visual skills for adaptation to digital world
Visual-spatial intelligence: includes your ability to visualize, remember images and details, and an awareness of your surroundings