Bell peppers are mainly made up of water and carbs. Most of the carbs are sugars, such as glucose and fructose. They are also a decent source of fiber. They are naturally high in antioxidants to include (capsanthin, violaxanthin, lutein, quercetin and luteolin)
Bell peppers may have many health benefits. These include improved eye health, reduced risk of anemia and some chronic diseases. When eaten in moderation, bell peppers do not have any adverse health effects. However, they may cause allergies in some people.

Source info: https://authoritynutrition.com/foods/bell-peppers/