What does this song mean exactly?

It's been a long time that I've been listening to The Fray's song: How
To Save A Life and it's like one of my most favourite songs.

I never really understood the lyrics yet I liked it..like, ALOT! And
just all of a sudden today, I'm dying of curiosity as to what this
song means?

A helpful answer would be immensely appreciated and of course, would
get the incredible "10 POINTS!"

So, Please and Thank You? :D