Soldiers Adapt Actions to the Situation in Chinese / Japanese...

This Chinese military proverb means, counter soldiers with arms and counter water with an earthen dam.

兵來將擋水來土掩 is about how different situations call for different actions. You must adopt measures appropriate to the actual situation.

To explain the actual proverb, one would not attack a flood of water with gunfire, nor would you counter-attack soldiers by building an earth weir. You must be adaptable and counter whatever threatens with relevant action.