这件 (zhè jiàn) combines the demonstrative 这 (this) with the measure word 件 (jiàn). It is used before nouns that are counted with 件, primarily matters and affairs (事), items of clothing (衣服), and pieces of luggage. 这件事 (this matter) and 这件衣服 (this garment) are among the most frequent combinations in everyday Mandarin.