“It's just a spark,
But it's enough, to keep me going”

Paramore – Last Hope Lyrics on LyricsMode
She see's a spark and realizes that it is a spark of hope and she knows that eventually the spark will turn into a flame and she will be a full blown fire, and she just has to wait until it gets to that.
We're all lost in a dark world. But if you see a spark, a tiny bit of light, it's enough to keep you going and make you unlost.