how to display headline on user profile?

Hi

I can't get my head round the unique field called "Headline". What does it do ??..
When I added some value in the filed for a certain user and opened its profile, I can't see it anywhere.

I found this doc, However it is still not clear for me...
Ihttp://docs.easysocial.io/administrators/profiles_custom_fields/headline_field

Its default description says "Set a headline to your profile", not saying anything about profile complete.

Could you please shed a light ?

Many thanks