I leaned alone in the dense bamboo, playing the piano and humming a song.
It's too light for anyone to hear, except my partner, Mingyue.
This poem is about the poet playing the piano, whistling and accompanying the bright moon in the bamboo forest alone.
The first two sentences describe the poet's actions such as "sitting alone", "playing the piano" and "whistling", while the last two sentences describe the quiet night and the bright moon, which constitute the beautiful and elegant artistic conception of the whole poem and convey the poet's quiet and indifferent mood.