Thanks for your answer.
Unfortunately it is a part of a short story written by James Joyce, who, as you may know, is not easy to read. The paragraph goes like this.
"And the sub-matron and two of the Board Ladies had heard the compliment. And Ginger Mooney was always saying what she wouldn´t do to the dummy who had charge of the irons if it wasn´t for Maria. Everyone was so fond of Maria".
These are the sub-matron and Board Ladies of what institution. Is it an orphanage, or a school or something else? Would you summarize the 'compliment" in your own words?
Do you have any idea what the 'irons' are? Are they irons used to iron clothes, or something else?
"What she wouldn't do to" is an implied threat. If given a chance, Ginger Mooney would do something harmful or painful to the "dummy who had charge of the irons". But that isn't the part you are asking about.
As is made clear a bit later on in the story, Maria works in the 'Dublin by lamplight' laundry, an institution set up to rescue prostitutes and alcoholic women from their destructive lives. The irons, then, as Cagey suggests, are irons for ironing clothes: noun meaning 3 in the WR English dictionary.
So the "dummy in charge of the irons" presumably controls who can use the irons and when. Ginger is being rude about that person by using the word "dummy": it means "idiot", or "stupid person".