It helps to know a couple of words to get by before you go. Hola (hello) Gracias (Thank you) and Cuanto cuesta (How much is this?) are three you will use A LOT.
It is a good idea to download a couple of apps before you go to practice the language and learn a few quick things when you are on the plane. Duolingo, for example, is a perfect app for this.

There are many sites in
Barcelona you HAVE to see; Antoni Gaudi (to the right) -Note-it’s free!,
Palace of Catalan Music (Palau de la Musica Catalana),
Basilica of the Sagrada Familia,
Casa Batllo,
Guell Palace (Palacio Guell),
Gothic Quarter (Barri Gotic),
St. Mary of the Sea Cathedral (Iglesia de Santa Maria del Mar) and
Magic Fountain (Font Magica) – Amazing to see at night. For a little culture, these places are incredible. For a little party, you must visit the top 10
clubs in Barcelona. But remember to always have your wits about you.
Some other awesome clubs with a range of music, filled with locals found in the Gothic Quarter (old town) include
Macarena Club - a shoebox-sized techno club that sits right next to the Ramblas. Keep in mind, it has great soundstages too;
Marula Cafe - an intimate club in Barcelona's city centre offering jazz, funk, soul, disco and Latin;
Sidecar Club - an eclectic club that sits in Plaza Reial and is quite unique;
Harlem Jazz Club - brings jazz, funk and soul to its faithful followers nearly every night of the week; and Cathedral (a must visit)- full of great house music and always a large local crowd. Great clubs in El Raval include;
Boulevard Club - a nice and loud club sitting right in the middle of the Ramblas;
Moog Club - an atmospheric techno club that sits a minute's walk from the Ramblas as well. Clubs in the beach and port area are pretty fun as well but not ideal if you’re on a budget as this area can get very expensive very quickly.
CDLC Club - one of Barcelona's most exclusive and glamorous beach side clubs and
Mondo Club - sits slightly further from the beach front than the other port clubs. It has a terrace area overlooking the yachts. Pretty fancy;
Shoko Club - a beach front club, bar and restaurant that is popular amongst the holiday crowd;
Catwalk Club - one of the largest beach clubs, attracting international house DJs. Clubs in Poble Nou include;
Razzmatazz – HUGE and awesome club containing five stories and is arguably Barcelona's most famous club, so it’s a must see (as seen below). If you’re in Poble Sec;
Apolo Club is actually two clubs in one. Both offer pretty new music and a great atmosphere. Clubs in Montjuïc such as;
La Terrrazza Club, which is a large outdoor club in the centre of the Poble Espanyol complex -Great for all night summer parties; as well as
The One Club, which is a small club with a big sound system and impressive light shows in the same area.
I have added a link - click on 'Barcelona' to find out more to do there. There’s just so much.