What and where is the gallbladder?

The gallbladder a small green sace located in the upper right quadrant of the abdominal cavity under the liver. (Another way to describe the location is under the lowest ribs on the right side of your abdomen.) It's a sac that receives and stores bile from the liver and has a duct that empties the bile into the digestive tract's small intestine (duodenum). The bile provides an emulsifier of fats/lipids to aid in digestion.
'Gall bladder' means a muscular sac attached to the liver that stores bile (secreted by the liver) until it is needed for digestion

The gallbladder is located behind the liver on the right side of the rib cage. It hits up against the under surface of the liver. There is a duct from the liver to the small intestine which is joined by a duct from and to the gallbladder. Bile moves in both directions into and out of the gallbladder through the cystic duct. This latter duct joins with a duct from the pancreas on its way to the small intestine carrying pancreatic enzymes also used for digestion. The main duct is called the common bile duct. It is common to the liver, gallbladder and farther down line, to the pancreas as well.

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It is located on your right side.
The Gal Bladder is located on the right hand side of the body, right below your chest.