Bek Se Ju is a traditional Korean white wine, brewed from ginseng and various other herbs. It has a sweet flavour, an acohol content of 13-15%, and is generally served chilled at lunch or dinner. Like most Korean drinks it is well served alongside spicy dishes, especially kimchi.
It's name translates to "The 100 year drink" (Bek Se = one hundred years, Ju = alcoholic drink), which is a reference to the supposed health benefits it bestows upon the consumer.
Since Bek Se Ju is more expensive than other Korean drinks, the cheapest and most popular of wich is soju, the two are often 50:50, resulting in Oh Sip Se Ju, "The 50 year drink."