I wondered too, I kind of thought of it ... like good job
mate as in... good job
friend
Like ... Your mate is your friend - ("I'm going to the pub with my mate") or a catch-all for anyone you're addressing somewhat affectionately. ("All right, mate?")
but I have lots two learn, I just found out my 1st floor flat is really on the 2nd floor

Very Chuffed to grow my British slang !
So can a bird, be a mate lol
, have to have the brits tell us...
One of the fun things here... about our international family !