This is the fourth book in the Chinese Characters for HSK series of text books. It covers all characters in level 4 of the HSK test (447 in total), using the simplified characters of modern standard Chinese. The book lists all HSK words which use those characters, up to level 6, totalling 1760 words.
Studying Chinese characters will aid in learning new words, allowing you to make connections between words and reduce the total learning (2663 characters in the HSK test levels 1-6, compared to 5000 words).