Push notifications?

Hi all, What are these push notifications? When i first joined this group it said they were unable to enable them and now they have popped back up again. They are asking to be enabled. Is this ligit or dodgy? I have never heard of them before.
Usually push notifications on apps are as far as I know so the app can check in the background to give you notifications like say your email app isn't open but you get a notification on your top bar to say you have an email. Or for Facebook or games etc

As far as I know its not working because I rely on emails to say someone's replied on here

Maybe someone could chime in

Sent from my SM-F926B using Micra Sports Club mobile app