Younger Son and I discussed this and came to the conclusion that it meant 'interesting vase in the window of a house in Mumbles':
Today the question arose again this time asked by Husband. He wasn't convinced by my answer.
'I think it means wine bar,' he said, 'and that's a carafe.'
'Huh! That's far less likely than my theory.'
I pondered for a while. 'Perhaps it means crafts. Or old things like Roman stuff.'
Thank goodness for Google. It does indeed mean pottery or crafts. But did you know there are 93 different symbols that can appear on brown signs? No, nor me. And you can see them all here.
It doesn't however explain the logo for the National Waterfront Museum.
It's puzzled me ever since they first opened it. I've imagined it's people - slightly bent people - looking at things.
'I think it's a factory with smoke coming from the chimneys, built on the letter M,' Husband said today. That would be reasonable as it's an industrial museum. But I still say it's not obvious.