Hundió means "sank" or "submerged". While it's the past tense of a common verb, its use in the phrase "se les hundió el barco" (their boat sank) is particularly powerful and metaphorical.
In the song, it vividly describes the complete collapse of a relationship or a person's emotional state, much like a ship sinking. This imagery makes it a memorable and engaging word that goes beyond its literal meaning, hinting at deep emotional turmoil and loss.
This song is about a woman who has been completely wrecked by a breakup. Ivan Cornejo starts by describing her as "Está dañada del amor" (She's damaged by love). Her hope is gone, her happiness is over, and she's so hurt that she feels nothing at all. The song says a "tipo sin luz se la apagó" (a guy without light turned hers off), which is a great way to describe how a bad relationship can dim your own shine.
Then Jhayco comes in with a solution, or at least a distraction. He sees her pain and offers himself as "los primeros auxilios" (first aid). He's not promising true love, because he thinks loving without being loved back is a form of suicide. Instead, he offers fun: trips to London, rides in his Bentley, and a very direct physical relationship. He wants to be the person she turns to now. His goal is clear in the final lines: when she's alone and crying, he hopes she sings his song, not the one that reminds her of her ex.