A group is usually made of 4 chords, i.e. 2 lines of lyrics. Groups of chords are separated with -. Notice the spaces surrounding the -, not to be confused with the measure separator.

For instance, if the chords for a given section are C G Am F - C G F C, you should play:

Chords Line
C G 1st line
Am F 2nd line
C G 3rd line
F C 4th line
C G 5th line
Am F 6th line
C G 7th line
F C 8th line

And so on…

Fraction Meaning Example
¼ A quarter of a measure X¼ means no chords for a quarter of a measure
½ Half a measure B B G# G#½ means 2 B measures and one and a half G# measure