Mañanitas is the diminutive form of mañana (morning), literally meaning "little mornings" or "early mornings". It's a tender and somewhat nostalgic way to refer to those specific times of day.
In the song, the artist sings, "me duelen esas Mañanitas que te vi llorando" (those early mornings when I saw you crying hurt me). This word choice evokes a sense of intimacy and regret, highlighting specific, painful memories rather than just general mornings. It adds a layer of emotional depth to his apology.
Have you ever been so sure of yourself that you completely missed what was right in front of you? That's exactly what Bachata Heightz is singing about in "Mi Tonto Corazón" [My Foolish Heart]. Our singer admits he was so confident he understood his partner that he got careless, paying attention to everything else in the world except her. He remembers her warnings now, and those mornings he saw her crying really hurt him.
He calls himself a "tonto" [fool] because he almost lost their love without even realizing it. He feels like a "payaso" [clown] whose destiny was like a "chofer que tenía por mal camino" [driver who took the wrong road]. He wishes he could erase his mistakes, but it's impossible. He thought he was a hero, but he was just a villain, letting their relationship fill with silence until it became a volcano. He's begging for forgiveness, deeply regretting the pain he caused, and pleading with her not to be cruel and to come back to him because only she can calm his heart.