military strategy; military tactics; originally refers to military classics Six Secret Teachings 六韜|六韬[Liu4 tao1] and Three Strategies 三略[San1 lu:e4]

to conceal one's strengths and bide one's time (idiom); to hide one's light under a bushel

“Six Secret Strategic Teachings”, one of the Seven Military Classics of ancient China 武經七書|武经七书[Wu3 jing1 Qi1 shu1], attributed to Jiang Ziya 姜子牙[Jiang1 Zi3 ya2]

military strategy and tactics; the imperial guard