SUMMARY
This is a love song, not necessarily for the opposite sex. This is a love song would sing to his bestfriend, buddy, mum, dad, or anyone who brought you sunshine. This song is about telling someone how much you love, thank,and cherish a person and how good of a person you think he/she is.
When you were Yellow(cowardly,afraid) they were the bit of yellow(sunshine, beacon of hope)for him. And now that that they are yellow (afraid, cowardly) and they need someone so bad, you would take your turn and become strong for them. You would go lengths and you'd risk everything, because you love them. You will be their yellow(hope).