The city of St. Gallen in Switzerland is named after Saint Gall, an Irish disciple who, according to legend, was followed by a companion bear. He appears on many old coins, but this is a modern medal created for the 200th anniversary of the renovation of the Abbey of St. Gallen.
I have never seen one of these medals in person, but the Internet seems to say:
Silver medal: 33 mm diameter, 15.1 grams, 0.900 fine, 0.437 troy ounces silver
Gold medal: 22 mm diameter, 7.3 grams, 0.900 fine, 0.211 troy ounces gold
(These are my best guesses. A jeweler can test your piece for gold or silver content.)
The medals are worth their weight in silver or gold, plus a small premium for rarity. To find the value, multiply the current price of precious metal by the metal content. For instance, gold is currently selling for $1140 US dollars per troy ounces (see kitco.com), so the gold medal is worth 0.211 x 1140 = $240 US dollars. You might add another $10 for rarity.
Beware of gold-plated silver medals, which are worth their weight in silver, not gold.