Without the tilde, años means something different. And I've never seen a green one.
The original song was written in 1962 by Carlos Paredes, THE Portuguese guitar master (in wikipedia
), as a soundtrack for the Portuguese film with the same name (directed by Paulo Rocha).
This is a new version created by his wife (Luisa Amaro) and friends on his tribute CD (Song for Carlos Paredes).
The correct song name is "Verdes Anos" (in Portuguese, with no tilde).
"Años" (with tilde) is the Spanish word for the Portuguese "Anos" (years) word.
"Verdes" is the plural for "Verde" which, in fact, means green. But also means tender which is more appropriate here (the film describes the sixties young generation in Lisbon).
The English film title was "Tender Years".