Not really correctYou (2nd person) got it, but one word in that sentence kept it patois lol.
In this case you wouldn't separate yah and so, it would be one word
yahso = here or right here.
yahso nice = here is nice
When you add the A it make it a little different.
A yahso nice means there's no other place to be, or you've been to other places and it's not happening like right here.