"Marinated olives" refers to olives that have been soaked or infused in a mixture of flavorful ingredients like herbs, spices, oils, and vinegar. This process adds extra taste to the olives, making them delicious and more interesting to eat.
And since each taberna has its own specialities, the ritual and the fun is stopping at two or more for a drink and maybe a small plate of marinated olives, deep - fried squid rings, or Gambas al Pil Pil, which are spicy, garlicky shrimp. (fieryfoodscentral.com)