Why does this staff contain 15 lines and how could I play this on a guitar?
The top 5 lines (staff) are the vocal melody. The next two staves are intended to be played on piano - broadly speaking one staff for the right hand, one for the left. Songs are often published in this format, even when the original version wasn't performed on just voice and piano.
In this case you'll observe the vocal part is duplicated in the top piano staff. In performance you probably wouldn't want to do this, but part of the convention of 'piano & voice' copies is to include the melody in the piano part.
A guitarist performing this piece would doubtless choose what's in the bottom stave, a specific rhythm using a B5 'power chord'.
It isn't always so easy to decide what to play from a piano/vocal sheet!
It's going to depend on what you want to do. The guitar part is actually written, of sorts, shown by the B5 chord window on top of the top stave. I expect (hope!) there will be others later in the song. So, the guitar part is there - chords - and an appropriate rhythm can be strummed while someone sings.
That someone will sing the words along to the tune written on the top stave.
As already mentioned, the other two staves are explicitly for piano, l.h. and r.h. The middle stave here is merely showing the melody line, which, if a pianist was accompanying a singer, would probably not be played as such, unless the singer was unsure of the tune! It's more of a plan so that, in the absence of a singer, a piano player can read the bottom two lines, and it'll sound o.k.
However, if you wanted to play the song on guitar, you could just read either the melody line (top) or the middle line, which here is the same - but not always. Forget the bottom line, as on guitar, some of those notes are too low. There's no simple way round it for this song, but for a similar one in a different key, say E, you could tune the A string up to B, and produce something like the 'drone' effect shown in the F clef, while still playing the melody, unencumbered, on higher strings. But then what happens when the harmony changes..?
It would be impossible to play this music, the way it's notated, on guitar since it's not written for guitar but a piano (bottom 2 staffs) and a singer (top staff).
What you can play on guitar is the top 2 staffs (which are the same) on their own because they use a terble clef.
The bottom staff uses a bass clef and would have to be transposed before you can play it on guitar.
Ideally you should learn guitar music or music arranged for guitar if you're learning guitar.