a way of writing ‘yes’ to show that the speaker has an upper-class accent (= a way of pronouncing the words of a language) 是，好（书写时用，表示带上流社会口音的 yes） used to show that you have a low opinion of somebody/something （表示评价低）啧，哎
Word Originsense 2 natural exclamation: first recorded in English in the early 17th cent.