Cadd(b9)G means a quick progression from Cadd9 to G, with Cadd9 counting for only 1 beat.  
This occurs elsewhere in the chords with the same rule applying.

Intro: G C9 - G C9 G/B C9 
G/B G D9 - D C9 G/B 
C9 G/B G

Verse 1:
G                   C9 - G
Close your eyes and count to three
C9   G/B   C9   G/B   G
I'm gonna make you proud of me
D
Not today but that's alright
C9   G/B   C9   G/B G 
C9 - G C9 G/B C9 G/B 
G - D9 - D C9 G/B C9 G/B G
We have got a long long time

G                       C9 - G
I've got big plans and you do too
C9   G/B   C9   G/B   G
And we've got ways to make them true
    D
When I get old and if I do
C9   G/B   C9   G/B G C9 - G
I'm gonna get there next to you

           C9    C
And you can count on me
           G
And you can lean on me
          D            D4  D   C9
And we can throw our dreams to the wind
C9   G/B   C9   G/B G 
C9 - G C9 G/B C9 G/B 
G - D9 - D C9 G/B C9 G/B G
They'll find us again

G              C9 - G
With a hand to hold the rail
C9   G/B   C9   G/B   G
Count the years that we've got left
D
We've got the world by the tail
C9   G/B   C9   G/B G C9 - G
Oh we just don't know it yet

           C9    C
But you can count on me
           G
And you can lean on me
          D            D4  D   C9
And we can throw our dreams to the wind
           G
And you can count on me
           C9
And you can lean on me
          D            D4  D   C9
And we can throw our dreams to the wind
C9   G/B   C9   G/B G  C9 - G
They'll find us again
C9   G/B   C9   G/B G  C9 - G
They'll find us again
C9   G/B   C9   G/B G  C9 - G
They'll find us again