Gwàa (กว่า) has a few different uses — understand them by ear here. After an adjective it is the "-er … than" that English builds into the word itself; at the front of a clause, as กว่าจะ, it is either "by the time…" or the whole stretch of getting there — กว่าจะถึงที่นั่น…, "it takes nearly six hours to get there"; and ยิ่งกว่านั้น is a set phrase for "more than that".