"This is a cold bathroom."
Translation:هٰذا حَمّام بارِد.
I'm not sure I understand the significance of the little ا above the ه. I've not seen that before in standard written Arabic.
It denotes that it's pronounced "haa", and not "hu", for example. It can't be written as هاذا. So, this diacritic is necessary to show the correct pronunciation. I don't know about normal writings but it's used in Koran and is a standard diacritic.