English translation: Water not only floats a boat; it also sinks it.
Meaning: This is a proverb about 'yin' and 'yang', a central idea in Chinese philosophy. Many things in life have opposite properties; for example, we need water to live, but we can also drown in water. To get through life we need to form relationships with other people; however, relationships can also hurt us. The sun gives us light, vitamin D, and .... skin cancer. Although bacteria make us sick and can even kill us, there are 'good' bacteria that our bodies need to be healthy. Finally, in the words of another proverb: Fire is a good servant but a bad master.
For further reading about 'yin' and 'yang', see the links below:
The philosophy and theory of yin and yang
Yin yang, two symbols
Thanks to my student Qian Gao for sharing this proverb