The organ you are referring to is the gallbladder.
The gallbladder is a small, pear-shaped pouch located beneath the liver. Its primary role is to store and concentrate bile, a digestive fluid produced by the liver that helps break down fats in the food we eat. When you consume a meal, especially one that is high in fats, the gallbladder releases bile into the small intestine to aid in digestion.
Although the gallbladder plays a significant role in digestion, it is not essential for life. If it is removed due to gallstones or other health issues, the liver continues to produce bile, but it flows directly into the small intestine rather than being stored. This can lead to dietary changes, as the body may have a harder time digesting high-fat meals without the concentrated bile from the gallbladder.