Intelligence is defined as general cognitive problem-solving skills. A mental ability involved in reasoning, perceiving relationships and analogies, calculating, learning quickly… etc.
Earlier it was believed that there was one underlying general factor at the intelligence base (the g-factor), but later psychologists maintained that it is more complicated and could not be determined by such a simplistic method. Some psychologists have divided intelligence into subcategories. For example Howard Gardner maintained that it is comprised of seven components: musical, bodily-kinesthetic, logical-mathematical, linguistic, spatial, interpersonal, and intrapersonal. Other definitions are: “Intelligence is what you do when you don't know what to do.” “Intelligence is a hypothetical idea which we have defined as being reflected by certain types of behavior.”
Defining intelligence https://www.youtube.com/watch?v=AwMY7cbKU3c