Lunch (la Comida) is what Spanish living is all about.
Between 1:30 and 4:00pm, Spain shuts down and chows down. Some of the greatest joys of Spanish life are found either here within (3 or 4 course meals as a daily occurrence) or shortly after this gargantuan meal in the form of world's greatest invention: la siesta.
Most restaurants have what we would say is a Price Fixed meal. What this entails is an appetizer or 1st course ("primer plato"); an entrée or 2nd course ("segundo plato"); bread; a drink-wine, beer, mineral/bottled water, soft drink, etc; and dessert. Some variations do exist in that some places might stiff you on bread and drink (for a convenient surcharge) or possibly (but VERY rarely) on dessert. Watch out for this one when you read a menu on the door outside the restaurant.