Hello everyone.

I'm totally new to this site - I'd really appreciate your help.

I've been asked the following:
Whether "YATTA" is the Irish word for mother's or momma's.
well, I've been using the dictionary which says "MÁTHAIR"
so I was wondering whether this is possible in any way. Is it Irish at all?
I hope I was able to read the word right, it could be "YATTA" or "YAHA".

Thank you for your time and help!

Definitely not.

But somebody may have heard the lenited form of máthair

a mháthair

and misheard.

"YATTA" is a Japanese word meaning "Done!" that gained some currency in the early Naughts on the back of a cheesy Internet meme. I think you may have been trolled.