Homely in Ireland and the US mean two completely seperate things. They present two completely different images and even feelings or emotions to the listener.

Homely in Ireland is complimentary it conveys down to earth, grounded and stable. Not too fancy.. as in..."the hotel was a homely little place"
It niether means attractive or unattractive, it does not mean ugly but rather something pleasant and welcoming, it simply conveys a person with a welcoming spirit, a comfortable person.
If referring to a woman..
..she was a homely soul. It is not referring to looks but a feeling or emotion one might get upon comparing woman not in looks but in mannerisms.

It simply means she doesn't act like a slut.

If it refers to looks in any way it would simply mean she's not slutty looking it is more or less how she dresses that makes her homely not her actual facial features or shape or size or hair color.
She's the girl next door. Common, average, but if she wanted to she might pretty herself up just as pretty as any slut if she dared to. But that's not her style she prefers to be homely. She likes being homely. She doesn't want all the attention the slutty girls long for. She's happy and content being nobody. She's homely. She's humble, not seeking fame, not an attention whore, normal like a girl should be. Down to earth, nice to be around, unoffensive, a girl that anyone could converse with, to some guys a homely trait or character can be rather attractive. It does not mean ugly.