Daebak (대박) is a Korean exclamation that denotes approval. It is often translated as “awesome”. As stated on The Korea Blog, it might also be used as “a way of greeting, particularly to wish someone good luck or success.” The blog expands on the definition, adding that “daebak is also used when a situation brings upon great mirth and laughter. When a joke is a big hit. When something is astoundingly funny or hilariously bizarre. In short, daebak is a good thing. It’s awesome, great, incredible, memorable, funny, and happy; it’s an exclamation of observation, sharing of emotion, a compliment.”

It might be considered a slang, since it is mostly used by people from younger generations.