Sellaron comes from the verb sellar, meaning 'to seal'. It's an interesting word because it goes beyond a simple 'kissed' or 'agreed'.
In the song, it's used twice: first, "Sellaron todo, todo con un beso" (They sealed everything, everything with a kiss), and later, "Sellaron todo con un beso." This repetition emphasizes the profound commitment and finality of their actions, suggesting their love was so powerful it 'sealed' their fate and their world together.
"11 y 6" tells the story of two strangers who meet by chance in a cafe, both worn out from life, and fall into a secret love affair. Fito Páez sings about them tiptoeing to windows, sneaking off to walk down Corrientes (Buenos Aires' famous downtown avenue), and hiding together in the center of the city and in a bar's bathroom to steal a kiss.
For a month they sell roses and live only for each other, keeping their romance hidden from everyone. The narrator never finds out exactly what they were carrying between them, or what happened after — he simply never saw them again. The title's numbers, 11 and 6, are left deliberately mysterious, a private detail that belongs only to the two lovers.
It's a song about a love so intense it feels bigger than mythology itself ("stronger than Olympus"), and about the bittersweet mystery of a romance that burns bright, stays secret, and then disappears without explanation.