Translation:Their band played six melodies in the concert.
I recently attended a violin masterclass here in Romania (I've only lived here a bit less than two months, so don't understand much of the language yet), and noticed that the verb "a cânta" was used when asking the participants to play on their violins. Is this common usage in the world of instruments, in this case stringed instruments, to use"a cânta" when referring to playing an instrument (as opposed to singing with one's voice)?
Yes, Romanian uses the same verb to describe singing and playing an instrument (eu cânt - eu cânt la vioară/ la pian/la chitară/etc.). French uses "jouer" which is similar to "to play" ( je chante - je joue du violon). Italian uses "suonare" (more or less "to sound") ( io canto - io suono il violino)
Melodii can be translate to mean melodies as well as songs. In reality, a song can have multiple melodies, so this translation should be six songs. In response to Lajos905235, depending on the length of each song, a set (the time a band plays) could in fact be only six songs. If you have ever listened to the band Yes, their song "Close to the Edge" was a entire side of an album, almost 30 minutes long.