Meaning: To prepare for disasters that have not yet happened, to plan everything well, to have the outcome under one's control, and to decide the outcome thousands of miles away.

Be prepared for a rainy day: It means to make plans before things happen.

Managing strategies: refers to a person who is very capable and can always control the overall situation no matter what problems he encounters.

Win a decisive victory thousands of miles away: Generally speaking, ancient generals can predict the battle situation thousands of miles away while sitting in their military tents.

This famous quote comes from "Historical Records: The Benji of Emperor Gaozu". It was originally a word praised by Liu Bang, the emperor of the Han Dynasty, to the counselor Zhang Liang.

It means that if you want to win the battle, you must be good at strategizing and planning and commanding. Only in this way can you ensure victory. Being good at strategizing will often have the effect of getting twice the result with half the effort.