Decantar literally means "to decant", a process of allowing sediment in a liquid, like wine, to settle. It's a sophisticated and uncommon word to find in a pop song.
Shakira uses it in a beautiful metaphor for healing. She sings that life itself will "decantar la sal que sobra del mar" (settle the excess salt from the sea), poetically suggesting that life will naturally filter out the pain and sorrow, leaving peace behind.
Shakira wrote this sweet pop track as a direct love letter to someone carrying heavy emotional baggage, and she makes it her personal mission to patch them right up. She kicks things off remembering the exact moment they met, singing, "Te conocí un día de enero / Con la luna en mi nariz" (I met you one day in January / With the moon on my nose), falling headfirst because she could tell they were sincere. She spots the old emotional damage right away: "Ya te encontré varios rasguños / Que te hicieron por ahí" (I already found several scratches / That they gave you out there). But instead of running from it, she steps up, declaring that her love is the best doctor in town to heal that grieving soul and leave it brand new.
What makes this song extra charming is how she brings in quirky cultural details and comic strips. She compares the pair wandering through the world to "Eneas y Benitín" (the Spanish-language comic strip duo known in English as Mutt and Jeff). She also notices their cultural differences: while she asks "¿cómo dices?", her partner uses Argentine Spanish phrasing with "¿qué decís?" (what do you say?) and tears up listening to a traditional tango instrument: "Y lloras de emoción / Oyendo un bandoneón" (And you cry with emotion / Hearing an accordion-like bandoneon). It is an encouraging, cozy track built on a simple promise that time and love will wash away the hurt, just like life filtering the excess salt out of the sea.