There's plenty of songs in ASOS, but "The Last of The Giants" has always perplexed me. Jon is similarly confused after hearing the Wildlings' sing, saying that there must be hundreds of giants traveling with Mace's band. Then Ygritte tears up and exclaims "you know nuthing, Jon Snow."

But Jon has a point. There may not be many giants, but there isn't only one left either. Also, it's not the giants who are singing this song, but the Wildlings themselves. So what is its meaning? Does it represent the slow death of the old Wildling ways, or is there something else to the lyrics:

Ooooooh, I am the last of the giants,

my people are gone from the earth.

The last of the great mountain giants,

who ruled all the world at my birth.

Oh the smallfolk have stolen my forests,

they’ve stolen my rivers and hills.

And the’ve built a great wall through my valleys,

and fished all the fish from my rills.

In stone halls they burn their great fires,

in stone halls they forge their sharp spears.

Whilst I walk alone in the mountains,

with no true companion but tears.

They hunt me with dogs in the daylight,

they hunt me with torches by night.

For these men who are small can never stand tall,

whilst giants still walk in the light.

Oooooooh, I am the LAST of the giants,

so learn well the words of my song.

For when I am gone the singing will fade,

and the silence shall last long and long.

Edit: I think there's something to what some commenters are saying: the 14 foot tall giants that travel with Mace may not be the same giants of the song. None of the giants we have seen are capable of fluent speech in the common tongue of Westeros. Similarly, you probably wouldn't describe any of them as "great mountain giants". The "great wall through my valleys" is most likely the Wall, which is the one concrete detail tucked into the lyrics. So, is that some Wildling bard's poetic license or are we getting some deeper hints into what the North was like before the Wall and the Long Night?