No rain, no flowers essentially means that growth sometimes comes from struggle, pain or challenge. Although rain is not necessarily beautiful, plants bloom and use it to give full play to their advantages. They embrace the rain as it is and thrive on it.
Suffering is always painful, but when you get through it, you will find that success is behind it. Everyone’s life has to experience one difficulty after another. We can get honed from difficulties. Only honing can make us progress, and only honing can make us succeed.