'une truite' is a trout in French. 'le vin jaune' (the yellow
wine) is a particular type of wine, made in the Jura region in
France. You cannot really drink it as a wine as it has a very
strong perfume due to the production process (the air lost through
the wood of the barrel isn't replaced with wine, so a different
maturation takes place). So the 'truite a vin jaune' is a recipe of
trout involving some of that 'wine' put in the sauce while you are
cooking it.