Does the highlighted sentence mean "neon signs contain and represent a feeling of life in seaside"?
Context:
the use of pure candyfloss coloured light and molten autography creates an emphatic exhilaration of Emin’s text. For those coming from an English seaside town such as Margate, as Emin does, neon may be the seaside font of the soul, the light by which feelings are illuminated.
The "font of the soul" is the place from which the soul originates. e. illuminated signs.
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The "font of the soul" is the place from which the soul originates. "neon" refers to neon lighting, i.e. illuminated signs. The word "seaside" adds the idea that this "font" is located at the seaside, and applies to people who come from a seaside location. Needless to say, this is all highly fanciful (I would say pretentious).