The song that Winston hears the prole woman singing out of the window of Mr. Charrington's rented room could mean a variety of different things. The first stanza refers to the power of a mere glance in stirring up dreams and emotions--this ties in to Winston's thoughts and feelings about O'Brien. O'Brien merely glanced at him, but in that glance, he sensed that O'Brien knew things, things about the rebellion, about how to lash out against the party, and that he felt the same way that Winston did. That hope was enough to haunt his dreams and stir his excitement quite a bit.
The second stanza is a bit more vague, and could refer to a number of things. It mentions how "time 'eals all things," or, at least is supposed to, but how
"the smiles an' the tears acrorss the years they twist my 'eartstrings yet."
So, time really doesn't heal all things; the pain and joy of times past still twist the heartstrings, or, hurt and bring back pain or happiness when we think upon them. This could be referring to Winston's mother and sister, and the overwhelming sense of guilt that he feels about their disappearance. Every time he thinks of them he is pained by it, and has a hard time feeling so responsible, whether he was responsible or not. He has nightmares about them all of the time. So, it could refer to how time has not dampened the pain of their loss. It could also be a sense of foreshadowing, how, later in the book, Winston is driven to let go and abandon those things that he holds most dear, and how time doesn't make him forget those things, but the Party will do its best to make him forget. It could foreshadow how Winston, given time, is able to completely reshape the way that he thinks about the world. One last possible meaning is that a lot of people who live in their society still remember what it was like before the Party was all-powerful, and they still long for the "good ol' days"; time hasn't dulled their memories of it.
I hope that those thoughts helped; good luck!