Barcelona is full of restaurants and just about anything you could want is on offer. Many bars serve tapas, and there are a good number of Basque tapas bars where you can eat some really tasty morsels while drinking. The price can quickly add up though and it is usually cheaper to eat at a restaurant.
There are many places offering typical Spanish or Catalan cuisine, including paella. The quality can vary enormously, but Barceloneta is renowned for its seafood. And there are several highly regarded restaurants offering a modern take on Catalan cuisine.
Catalan basics include things like pa amb tomàquet (bread smeared with tomato, salt and olive oil), botifara (a spicy pork sausage), escalivada (roasted red peppers, onion or aubergine). Other dishes include mar i muntanya (sea and mountain), combining meat with seafood, specialities like calçots, a type of spring onion that is cooked on an open fire and served with a sauce, and suquet, a seafood casserole.