Olives are fruits. They grow on trees, and have been cultivated in the Mediterranean for thousands of years. They are the most widely cultivated fruit crop in the world, Mostly in the mediterranean zone.
An olive is a fruit and its not a vegetable. It is a fruit from a tree called Olea europaea. It has a bitter taste. Its generally used in agriculture in Europe and North Africa.
Olives are the fruit of olive trees. Specifically they are drupes which are types of fruits that have a fleshy outer surrounding a seed, like peaches and apricots.
I am not a botanist, but I think it is a fruit because it has a seed inside, like a peach or a grape or a pear. Because it is savory, we tend to think of it more as a veggie.