What does 8va?

8va means one octave higher - 8va basso means one octave lower (I've never seen it abbreviated 8vb, but some publishers might do that) ...When you see 8va above the RH, it means play everything under the - - - - - - - - line ONE octave higher than it is written. An octave up is just 12 frets higher. Sometimes solos that are played up beyond the 12th fret are written out as if they were played lower and then marked with the "8va" mark