Otoño means 'autumn' or 'fall'. While it's a common word for the season, its use in this song is beautifully poetic and unique.
Jeanette sings, "Y en sus ojos de otoño / Dormir poco a poco" (And in his autumn eyes / To slowly fall asleep). This evocative phrase suggests the boy's eyes are not only brown but also hold a deep, gentle melancholy, much like the autumn season itself.
Have you ever spotted a stranger across the room who looked so hopelessly downcast that you immediately wanted to save them? That is the exact story Spanish singer Jeanette tells in "El Muchacho De Los Ojos Tristes". While slow dancing with a mysterious young man, she notices there is not a single smile or trace of light in his deep gaze ("Ni una simple sonrisa / Ni un poco de luz en sus ojos profundos"). Even though she does not even know his name ("Ni su nombre conozco"), his quiet melancholy pulls her in right away, turning a stranger's distant sorrow into an instant rush of affection.
What makes the song fun is how boldly dramatic her mission becomes. She compares his quiet gloom to "ojos de otoño" [autumn eyes], yet she instantly decides she is the cure. By the chorus, she is convinced he needs to see her as much as he needs air ("Como el aire necesita verme"), while she needs him like the sun. Her master plan is simple: unlock the strange mystery behind his gloomy face and make his sad eyes laugh using her kisses and tender love ("hacer que su mirada ría / Con mis besos y mi gran amor"). It is sweet, dramatic, and pure classic pop romance.