Seolleongtang is one of Korean Traditional Food.
Seolleongtang is made by boiling down a cow’s bones, feet, head, internal organs, brisket and shank. Seolleongtang is boiled more than 4~5 hours.

The origins of Seolleongtang can be traced to the ceremony, which the king and his retainers in Spring, to honor the god of farming. The ceremony was held at Seonnongdan, outside of Dongdaemun in Seoul. During the ceremony a cow would be killed in sacrificial offering, and afterwards this cow would be made into a soup. The word “seolleongtang” stems from Seonnongtang, which means soup boiled at Seonnongdan. Later, the word seonnongtang evolved into seolleongtang. – from Korea Tourism Org

Normally Seolleongtang is sold at Seolleongtang specialty restaurant.
Price is 6,000 KRW ~ 10,000 KRW. I can write a average price is 7,000 KRW ~ 8,000 KRW.
When you odrer Seolleongtang, normally restaurant serve 2 or 3 side dishes, one of rice and Seolleongtang. Side dishes are Kimchi and Kkakdugi. Restaurant prepare several seasoning such as salt, dired red pepper powder, ground pepper and chopped green onion.
I recommend put a salt and chopped green onion.
Put rice into Seolleongtang. If you can eat Kimchi and Kkakdugi, they will make more good taste.

I do not have idea how to describe a taste of Seolleongtang.
I can tell you Seolleongtang is not spicy, it just a kind of soup made from cow’s bones. I guess Seolleongtang is not hard to eat, reason is you can season by your self.
Seolleongtang is Korean Traditional food and really slow food, it is good for your health.
I strongly recommend taste Seolleongtang, if you are in Korea.