胜败乃兵家常事

胜败乃兵家常事

Literally means:

for military commander, winning or losing battle is a common occurrence

Actually means:

Victory or loss is normal to a militarist. This sentence metaphorically means that either victory or loss is common occurrence. It is often used to reassure one that a temporary setback means nothing, and that he must not lose confidence.

胜利和失败是军事家经常碰到的事。比喻成功和失败是常有的事。多用来强调对挫折或失败要想得开，尤其是不能因此失去了信心。