HSK’s meaning from Wikipedia:
The Hanyu Shuiping Kaoshi (HSK; Chinese: 汉语水平考试; pinyin: Hànyǔ Shuǐpíng Kǎoshì), translated as the Chinese Proficiency Test used in Mainland China or the Chinese Standard Exam used in Mainland China, is the standardized test of Standard Chinese language proficiency of China for non-native speakers such as foreign students and overseas Chinese.
I think this is a Chinese-style textbook, that means this book is not suitable for self-learning, you need a teacher to teach you
