Hundida literally means "sunk" or "submerged." While it can refer to physical sinking, it's often used metaphorically to describe a deep emotional state.
In this song, Christian Nodal uses hundida to paint a vivid picture of someone completely overwhelmed by loneliness, singing "Estás hundida en la soledad" (You are sunk in loneliness). This powerful imagery makes the word memorable and conveys a strong sense of despair and being trapped.
"Ahora" ("Now") catches Christian Nodal past the crying, looking at a breakup with a clear head. Over a slow mariachi arrangement he opens already numb: "Ahora que se secó mi llanto" ("Now that my tears have dried"). When he imagines her coming back, there’s no relief in it: "Y es que el que vuelvas no me causa ilusión" ("And your return doesn’t excite me").
The chorus turns questions into answers he couldn’t say before: "Por qué me dolió tanto amar" ("Why loving hurt me so much"), "Ahora claro todo está" ("Now everything is clear"). It’s a song about understanding exactly what went wrong, right on schedule for it to be too late to matter.