Traveling Soldier Lyrics

Could you please explain the meaning of the red phrases/sentences?

Lyrics: … hicks.html

[color=red]Two days past eighteen
He was waiting for the bus in his [color=red]army greens
Sat down in a booth at a cafe there
Gave his order to a girl with a bow in her hair
He’s a little shy so she gives him a smile
And he said would you mind sittin’ down for a while
And talking to me, I’m feeling a little low
She said I’m off in an hour and I know where we can go

So the letters came from an army camp
In California then Vietnam
And he told her of his heart
It might be love and all of the things he was so scared of
He said when it’s [color=red]getting kinda rough over here
I think of that day sittin’ down at the pier
And I close my eyes and see your pretty smile
Don’t worry but I won’t be able to write for awhile

Two days past eighteen = 2 days after his 18th birthday (the age at which you can join the military in the US)
army greens = army uniform
it’s getting kinda rough over here = it is dangerous, there is hard fighting in Vietnam

Thank you so much Mister Micawber.