I felt it was about dying, about regret. Brooklyn is heaven, or peace, or calmness. Like letting go of the battle against a terminal illness, addiction, or even old age. In the song, he's looking back on regrets. "I used my words to fight... such a waste of time." He's also flashing back on his best memory, his wife or loved one. "That Woman she's got eyes that shine.... " like saying how amazing she is and the pain of leaving her behind but still knowing it's his time to go. And throughout the song, "the hardest words to say.... I and love and you." Maybe he just can't bare to say it because of regret, shame, or heartache.