The rain in the sky has not yet explained its meaning, and the rivers and lakes are long, but there is always a time to meet.

Tianya refers to the sky, and rain is rain. Unsolved means that I don't understand my thoughts, and the rivers and lakes are far from timely means that there will always be times to meet.

This sentence expresses the expectation for the future and regret for life, implying that the road of life is full of unknowns and challenges, but there are also opportunities and beautiful moments to meet.