This sentence means "If you often walk by the river, your shoes will not get wet." It means that when you do something, you will inevitably encounter some difficulties or unsatisfactory situations.

The literal meaning is that when walking by the river, even if you are wearing shoes, it is difficult to avoid getting your shoes wet. Therefore, this idiom is used to describe that when doing things, we will inevitably encounter some difficulties and challenges. As long as we are prepared to deal with them, we can grow and progress through difficulties.

This idiom tells us that when facing difficulties, we should strengthen our confidence, be brave enough to meet challenges, and continue to learn and make progress in order to remain invincible in a highly competitive society.