Literally

For the line of the moustache to come through.

What it means

To be only just old enough to count as a man.

અર્થ

યુવાનીમાં પ્રવેશ કરવો, પૌરૂષભર્યુ કામ કરવાની ઉંમરે પગ મૂકવો

Heard it differently, or know we've got the sense wrong? Tell us — that is exactly the kind of correction this needs.