Also when you see lines, they indicate the courses of the lute above the 6 that are fretted. I believe I have heard of lutes having up to 24 strings? Maybe?
This sheet music is written in Lute Tablature, which is actually quite easy to read, cause the letters A, B, C, D, E, F, G,H,L, and K are used to designate the strings to play the lute. A is open, B is second fret, F is fifth fret, etc. I think that is how it goes. The tablature also has the note values displayed above the notes, which is like today's music notation. http://yoyo.cc.monash.edu.au/~mongoose/tab_read.html This is the site to gain a little about reading this tablature for lute. Hope this is enlightening... I also hope that I am right.