When combined, the characters literally mean “to falsely (虚) display (张) sound (声) and power (势).” The idiom paints a vivid picture of someone creating a loud and imposing facade to hide an underlying emptiness or weakness.
The concept of 虚张声势 is deeply embedded in Chinese strategic culture, heavily influenced by classics like Sun Tzu's “The Art of War” (《孙子兵法》). In this context, deception and psychological tactics are as important as actual military strength. An army might use this tactic—beating drums and waving banners on an empty hill—to make their forces seem larger than they are, causing an enemy to retreat without a fight. However, in everyday usage, the term carries a decidedly negative connotation. It implies that the person or entity is a “paper tiger” (纸老虎, zhǐ lǎohǔ)—all show and no substance. A Westerner might equate 虚张声势 with “bluffing” or “sabre-rattling.” While similar, there's a nuance.
虚张声势 is a common idiom used to criticize or expose someone's false bravado. Its connotation is almost always negative.