Do compound words like this often take the stress away from the usual penultimate syllable?
It's a town. From Wikipedia:
Welsh: Abergwaun, meaning "Mouth of the River Gwaun".
English: The town name Fishguard derives from old Norse fiskigarðr meaning "fish catching enclosure", indicating that there may have been a Scandinavian trading post, although no evidence has been found.
"fiski" means "to fish" and "garðr" means "garden" or "yard". "fiskigarðr" then means "to-fish yard" or "to-fish garden" which ends up meaning "fishing yard" or "fishing garden"
It's a place. See the only other thread on this page where this question was already asked and answered. The Wikipedia article linked there also talks about the origin of this name.