Tapas are best translated as small plates of food, often served at bars with beer or at restaurants with wine. While there are all sorts, this one is true to its Catalonian origins.
You can serve this as is, or you could it set up with some charcuterie elements like meats and cheeses. Either way, sharing a meal is certainly a good way to spend time with friends.
All you need to do is cut the tomato in half and rub it in circles on the bread, then drizzle with oil and sprinkle with salt!