Basically, when we describe something in English using an adjective, we'd use it together with the verb 'to be', i.e. It IS big. She IS pretty. They ARE smart. Does that make sense?
But in Korean, they will NOT use the verb 'to be' together with adjectives in this sense. The adjective itself will be the verb. Some examples...
ex #1...
to be pretty (in root/base form): 예쁘다
"She is pretty": 그 여자는 예뻐요 (Where '그 여자는' means 'She' as the subject - one of many ways to say 'she' - and 예뻐요 is the conjugated (into a polite, but not super formal) form of 'to be pretty'.)
ex #2...
to be big 크다 (in root form)
"It is big" 그거는 커요 (where '그거는' will refer to 'It' as the subject, and 커요 will be the conjugated - again, in a polite but not super formal manner - form of the descriptive verb 'to be big'.
Adjectives in Korean are actually used quite similarly to the way we use adjectives in English, going before a noun to describe it.
Hope that helps, but if it raises any more questions, let me know.
Rob...