The photo shows a restaurant called "Aralık Sonu Ocakbaşı" (meaning "End of December Ocakbaşı"). The joke is that Ocakbaşı is a popular Turkish cuisine, and this restaurant's name suggests that it only serves food during December. It's a humorous play on words that suggests the restaurant might not be very busy outside of December. The joke is in Turkish, and it uses the word "Ocakbaşı" in a funny way to imply that the restaurant is only open during December. This is a common type of humor in Turkish, which often involves puns and wordplay.