Just exactly what does this mean?

I have always wondered what the (4/5) means, for example...
Motley Crue - "Too young To Fall In Love" (version 3)


Does it mean that you hold that note/chord or what? I have heard that it means that it is a ghost chord, but what does that mean exacly? You can see in the above example that the 4/5 was just played so what is the deal?... humm. Does it mean that you hold that chord and let it ring out? I could just guess all night but it won't do me any good.

Can somene please explain it to me as if I was in 1st grade?

Much thanks to all.
Ghost notes i think, which is basically a note or notes that are played quickly and are barely noticeable when played during the song/riff whatever.
But there's no sense crying over every mistake, you just keep on trying till you run out of cake.

Or it can mean that you should let it ring a little before playing the next note.
Current situation:
Proud owner of Jackson JS30RR and Roland Cube 30X
So now I amreally confused... Do I play harmonic there, let it ring, or play a not that is only slightly noticable?

And how would you play a note that is barely noticable when I just played the same note(s) right before it?

My head is starting to hurt.