What do you mean the sunset belongs to mountains and seas and basketball belongs to teenagers?

This sentence expresses that young people are full of vitality and dreams after returning to the starting point after suffering.

"Sunset belongs to mountains and seas, and basketball belongs to teenagers" is a poetic and emotional statement, which means that the sun sets and the afterglow of the sunset is scattered all over the mountains and seas, just like all kinds of hardships and frustrations experienced in life, and finally they all return to the starting point.

Basketball in the hands of teenagers is a symbol of youthful vitality, and teenagers are full of vigor, passion and dreams. This sentence can be understood as: after all kinds of twists and turns in life, we will eventually return to the starting point, while teenagers have unlimited possibilities and futures.