They could use the setting to build up tension by having the setting around the main character's dangerous?
Don't want to play a sad song
Courageous and determined
The lines are explaining how even though our hearts are beating, they are beating us all the way to the grave. The heart beat is compared to the rhythm of a funeral march with everyone stepping in time. The lines are showing hearts are beating courageously and with determination all the way to the person's death, which is inevitable.
