Barcelona airport (Aeropurto de Barcelona) is located 20 km from the city center and is well accessible by multiple means of transport. Local name for the airport is Aeropurto El Prat which is based on the town that’s closest to the airport – El Prat de Llobregat.
Do you need to get to Barcelona city center from Girona? See my guide.
If the traffic is good, you can get from Barcelona airport to the city center in 30 – 40 minutes. It all depends on what’s your starting point (Is it terminal 1 or 2?), traffic density and period of the day.