Barcelona has an extensive public transportation system, including buses, metro, and trams. A single ticket costs €2.40 and is valid for one trip with transfers. Taxis are also available, but they can be expensive. If you prefer walking, most of the attractions are within walking distance.
If you have more time, you can add other popular attractions to your itinerary such as Casa Batllo, Casa Mila, or Montserrat mountain. On the other hand, if you have less time, you can skip the beach and focus on the cultural activities. Don't forget to wear comfortable shoes and bring a water bottle since it can get hot in Barcelona during the summer months.