Lyric discussion by Mozared 

Cover art for Unstoppable lyrics by Planet Smashers, The

This song is somewhat straightforward, according to me the key lies in the part that says;

"Are you waiting? The world, it falls apart They are unstoppable Are you, ready, to do, all that you can? And stop the unstoppable"

Basically they're saying like a lot of the (ska)punk bands out there that there's a huge 'wave' of big and powerful people messing up our world, and even though those people might be unstoppable, we should be "ready to do all that you can".